Carbocyclic nucleoside analogs

ABSTRACT

A compound of the formula: ##STR1## wherein A is a purin-9-yl group, a heterocyclic isostere of a purin-9-yl group, a pyrimidin-1-yl group or a heterocyclic isostere of a pyrimidin-1-yl group; E is hydrogen, --CH 2  OH or --OH; and G and D are independently selected from hydrogen, C 1  to C 10  alkyl, --OH, --CH 2  OH, --CH 2  OR 20  wherein R 20  is C 1  to C 6  alkyl, --CH 2  OC(O)R 21  wherein R 21  is C 1  to C 10  alkyl, --CH 2  OC(O)CH(R 22 )(NHR 23 ) wherein R 22  is the side chain of any of the naturally occurring amino acids and R 23  is hydrogen or --C(O)CH(R 24 )(NH 2 ) wherein a R 24  is the side chain of any of the naturally occurring amino acids, --CH 2  SH, --CH 2  Cl, --CH 2  F, --CH 2  Br, --CH 2  I, --C(O)H, --CH 2  CN, --CH 2  N 3 , --CH 2  NR 1  R 2 , --CO 2  R 1 , --CH 2  CH 2  OH, --CH 2  CH 2  OR 20  wherein R 20  is as defined above, --CH 2  CH 2  OC(O)R 21  wherein R 21  is as defined above, --CH 2  CH 2  OC(O)CH(R 22 )(NHR 23 ) wherein R 22  and R 23  are as defined above, --CH 2  CH 2  PO 3  H 2 , --CH 2  OPO 3  H 2 , --OCH 2  PO 3  H 2  and --CH 2  CO 2  R 3  wherein R 1  and R 2  are independently selected from hydrogen and C 1  to C 10  alkyl and R 3  is hydrogen, C 1  to C 10  alkyl, carboxyalkyl or aminoalkyl; or a pharmaceutically acceptable salt thereof.

This is a division of U.S. patent application Ser. No. 420,691, filedOct. 17, 1989, which is a continuation-in-part of U.S. patentapplication Ser. No. 319,385, filed Mar. 3, 1989, now abandoned which isa continuation-in-part of U.S. patent application Ser. No. 262,547,filed Oct. 25, 1988, now abandoned.

TECHNICAL FIELD

The present invention relates to novel compounds and compositions whichhave antiviral and antitumor activity, processes for making suchcompounds, synthetic intermediates employed in these processes andmethods for treating a host in need of antiviral or antitumor treatment.

BACKGROUND ART

Viruses are implicated in a variety of animal and human diseases.Numerous approaches have been proposed to combat these pathogens whichinclude, but are not limited to, herpesviruses 1 and 2 (HSV-1 andHSV-2), influenza viruses A, B and C (orthomyxoviruses), parainfluenzaviruses 1-4, mumps virus (paramyxovirus), adenoviruses, respiratorysyncytial virus, Epstein-Barr virus, rhinoviruses, humanimmunodeficiency viruses (HIV), polioviruses, coxsackieviruses,echoviruses, rubella virus, varicella-zoster virus, neurodermotropicvirus, variola virus, cytomegalovirus, hepatitis A, B and non-A, non-Bviruses, papoviruses and rabies virus.

One approach in the development of antiviral compounds has been toidentify compounds which interfere with the normal viral metabolism ofnucleosides. Because the structures of these compounds are usuallyclosely related to nucleosides which occur naturally in the mammalianhost, few have good activity against the virus without untoward sideeffects. Some of the few compounds having activity are very expensive toproduce. Thus, there is a continuing need for new compounds which act tokill viruses, to inhibit viral replication or to block the pathogenicactions of viruses.

The following references disclose various carbocyclic analogs ofnucleosides:

Ichikawa, et al., European Patent Application No. EP0330992, publishedSep. 9, 1989, discloses 2-hydroxy-3-hydroxymethylcyclobutyl substitutedpurines and pyrimidines having antiviral activity;

Zahler, et al., European Patent Application No. EP0322854, publishedJul. 5, 1989, discloses 2-hydroxy-3-hydroxymethylcyclobutyl substitutedpurines and pyrimidines having antiviral activity;

Slusarchyk, et al., European Patent Application No. EP0335355, publishedOct. 4, 1989, discloses 2,3-bis(hydroxymethyl)cyclobutyl substitutedpurines and pyrimidines having antiviral activity;

Tolman, et al., U.S. Pat. No. 4,782,062, issued Nov. 1, 1988, discloses9-((Z)-2-(hydroxymethyl)cyclobutylmethyl)guanine as a viral thymidinekinase inhibitor;

Kjellin, et al., U.S. Pat. No. 4,644,001, issued Feb. 17, 1987, and U.S.Pat. No. 4,548,818, issued Oct. 22, 1985, disclose cyclopropyl-,cyclobutyl- and cyclopentyl-substituted purine analogs which are usefulfor treating obstructive airway disease or cardiac disease;

Maccoss, et al., European Patent Application No. EP0184473, publishedJun. 11, 1986, discloses2-amino-9-((2)-2-(benzoyloxymethyl)cyclobutylmethyl)-6-benzoylpurine;

Albrecht, et al., U.S. Pat. No. 3,923,792, issued Dec. 2, 1975,discloses cyclopropyl-, cyclopropylmethyl- and cyclopentyl-substitutedcytosine analogs which are useful as antibacaterial agents;

Albrecht, et al., U.S. Pat. No. 4,016,267, issued Apr. 5, 1977,discloses cyclopropyl-, cyclopropylmethyl- and cyclopentyl-substitutednucleoside analogs which are useful as antibacaterial agents;

Ashton, et al., U.S. Pat. No. 4,617,304, issued Oct. 14, 1986, discloses((hydroxymethylcyclopropyl)methyl)-substituted purine and pyrimidineanalogs as antiviral agents;

Temple, et al., J. Med. Pharm. Chem. 5 866 (1962), disclosescyclopropyl-substituted purine analogs which are useful for treatinghuman epidermal carcinoma;

Masoliver, et al., C.A. 107:236375e, Spanish Patent No. ES519898,published Mar. 16, 1984, discloses cyclopropylmethyl-substituted purineanalogs; and

Marquez, et al., Medicinal Research Reviews, 6 1-40 (1986) disclosessubstituted-cyclopentyl nucleoside analogs.

DISCLOSURE OF THE INVENTION

In accordance with the present invention there are antiviral compoundsof the formula: ##STR2## wherein A is a purin-9-yl group or aheterocyclic isostere of a purin-9-yl group selected from the groupconsisting of ##STR3## wherein J and L are independently selected fromhydrogen, --OH, halogen, alkoxy, --SH, thioalkoxy, --N₃, ##STR4##wherein m is 1 to 5, --NR₁ R₂ wherein R₁ and R₂ are independentlyselected from hydrogen and C₁ to C₁₀ alkyl, --NHC(O)R₃ wherein R₃ ishydrogen, C₁ to C₁₀ alkyl, carboxyalkyl or aminoalkyl, --N═CHNR₄ R₅wherein R₄ and R₅ are independently selected from C₁ to C₁₀ alkyl,--N(R₆)OR₇ wherein R₆ and R₇ are independently selected from hydrogenand C₁ to C₁₀ alkyl, and --N(R₈)NR₉ R₁₀ wherein R₈, R₉ and R₁₀ areindependently selected from hydrogen and C₁ to C₁₀ alkyl; and wherein Mis hydrogen, C₁ to C₁₀ alkyl, halogen, ##STR5## wherein m is 1 to 5, or--NR₁ R₂ wherein R₁ and R₂ are as defined above; and Z is hydrogen,halogen, formyl, carboxyl, alkoxycarbonyl, carboxamido or cyano; or A isa pyrimidin-1-yl group or a heterocyclic isostere of a pyrimidin-1-ylgroup selected from the group consisting of ##STR6## wherein V is O orS;

Q is --OH, --SH, alkoxy, thioalkoxy, halogen, ##STR7## wherein m is 1 to5, --NR₁ R₂ wherein R₁ and R₂ are as defined above, or --NHC(O)R₃wherein R₃ is as defined above; and

T is hydrogen, C₁ to C₁₀ alkyl, 2-haloethyl, halomethyl, difluoromethyl,trifluoromethyl, halogen, cyano, nitro, vinyl, 2-halovinyl, alkynyl,hydroxmethyl, formyl, azidomethyl, 2-hydroxyethyl, --NR₁ R₂ wherein R₁and R₂ are as defined above, --NHOH, --SH, propenyl,3,3,3-trifluoropropenyl, 2-(alkoxycarbonyl)ethenyl, 2-cyanoethenyl,##STR8## wherein m is 1 to 5, or --CH₂ NR₂ R₂ wherein R₁ and R₂ are asdefined above; and

wherein E is hydrogen, --CH₂ OH or --OH; and

G and D are independently selected from hydrogen, C₁ to C₁₀ alkyl, --OH,--CH₂ OH, --CH₂ OR₂₀ wherein R₂₀ is C₁ to C₆ alkyl, --CH₂ OC(O)R₂₁wherein R₂₁ is C₁ to C₁₀ alkyl, --CH₂ OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ isthe side chain of any of the naturally occurring amino acids and R₂₃ ishydrogen or --C(O)CH(R₂₄)(NH₂) wherein R₂₄ is the side chain of any ofthe naturally occurring amino acids, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂Br, --CH₂ I, --C(O)H, --CH₂ CN, --CH₂ N₃, --CH₂ NR₁ R₂, --CO₂ R₁, --CH₂CH₂ OH, --CH₂ CH₂ OR₂₀ wherein R₂₀ is as defined above --CH₂ CH₂OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂ OC(O)CH(R₂₂)(NHR₂₃)wherein R₂₂ and R₂₃ are as defined above, --CH₂ CH₂ PO₃ H₂, --CH₂ OPO₃H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃ wherein R₁, R₂ and R₃ are as definedabove, with the proviso that when E is --OH then D is not --OH and withthe proviso that when E is hydrogen and D is hydrogen or C₁ to C₁₀ alkylthen G is not hydrogen or C₁ to C₁₀ alkyl; or a pharmaceuticallyacceptable salt thereof.

The term "C₁ to C₁₀ alkyl" as used herein refers to straight or branchedchain alkyl radicals containing from 1 to 10 carbon atoms including, butnot limited to, methyl, ethyl, isopropyl, n-butyl, isobutyl, sec-butyl,n-pentyl, 1-methylbutyl, 2,3-dimethylbutyl, 2-methylpentyl,2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl and thelike.

The terms "alkoxy" and "thioalkoxy" as used herein refer to --OR₂₅ and--SR₂₅, respectively, wherein R₂₅ is a C₁ to C₁₀ alkyl group.

The term "carboxyalkyl" as used herein refers to a carboxylic acid group(--COOH) appended to a C₁ to C₁₀ alkyl radical.

The term "alkoxycarbonyl" as used herein refers to --C(O)R₂₆ wherein R₂₆is an alkoxy group.

The term "aminoalkyl" as used herein refers to an amino group (--NH₂)appended to a C₁ to C₁₀ alkyl radical.

The term "alkynyl" as used herein refers to C₂ to C₆ straight orbranched carbon chain which contains a carbon-carbon triple bondincluding, but not limited to, ethynyl, propynyl, butynyl and the like.

The term "halo" or "halogen" as used herein refers to Cl, Br, F or I.

The term "aryl" as used herein refers to a monocyclic or bicycliccarbocyclic ring system having one or more aromatic rings including, butnot limited to, phenyl, naphthyl, tetrahydronaphthyl, indanyl and thelike. Aryl groups can be unsubstituted or substituted with one, two orthree substituents independently selected from loweralkyl, haloalkyl,alkoxy, thioalkoxy, amino, alkylamino, dialkylamino, hydroxy, halo,mercapto, nitro, carboxaldehyde, carboxyl, alkoxycarbonyl andcarboxamide.

The term "arylalkyl" as used herein refers to an aryl group appended toa loweralkyl radical.

The term "haloalkyl" as used herein refers to a loweralkyl radical inwhich one or more hydrogen atoms are replaced by halogen including, butnot limited to, fluoromethyl, 2-chloroethyl, trifluoromethyl,2,2-dichloroethyl and the like.

The term "side chain of any of the naturally occurring amino acids" asused herein refers to the functionality appended at the alpha carbon ofany of the naturally occurring amino acids and includes, but is notlimited to hydrogen (glycine), methyl (alanine), isopropyl (valine),hydroxymethyl (serine), benzyl (phenylalanine), and the like.

The term "heterocyclic isostere of a purin-9-yl group" as used hereinrefers to a heterocyclic group which has a similar structure and similarproperties when compared to a purin-9-yl group. In addition, theisostere may contain different atoms and not necessarily the same numberof atoms as long as the isostere possesses the same total or valenceelectrons in the same arrangement as does a purin-9-yl group. Forexample, well known isosteric pairs of molecules include the pair carbonmonoxide and atmospheric nitrogen and the pair cyanide ion and acetylideion. Heterocyclic isosteres of a purin-9-yl group include, but are notlimited to, compounds of the formula: ##STR9## wherein J and L areindependently selected from hydrogen, --OH, halogen, alkoxy, --SH,thioalkoxy, --N₃, ##STR10## wherein m is 1 to 5, --NR₁ R₂ wherein R₁ andR₂ are independently selected from hydrogen and C₁ to C₁₀ alkyl,--NHC(O)R₃ wherein R₃ is hydrogen, C₁ to C₁₀ alkyl, carboxyalkyl oraminoalkyl, --N═CHNR₄ R₅ wherein R₄ and R₅ are independently selectedfrom C₁ to C₁₀ alkyl, --N(R₆)OR₇ wherein R₆ and R₇ are independentlyselected from hydrogen and C₁ to C₁₀ alkyl, and --N(R₈)NR₉ R₁₀ whereinR₈, R₉ and R₁₀ are independently selected from hydrogen and C₁ to C₁₀alkyl; and wherein M is hydrogen, C₁ to C₁₀ alkyl, halogen, ##STR11##wherein m is 1 to 5, or --NR₁ R₂ wherein R₁ and R₂ are as defined above;and Z is hydrogen, halogen, formyl, carboxyl, alkoxycarbonyl,carboxamido or cyano.

The term "heterocyclic isostere of a pyrimidin-1-yl group" as usedherein refers to a heterocyclic group which has a similar structure andsimilar properties when compared to a pyrimidin-1-yl group. In addition,the isostere may contain different atoms and not necessarily the samenumber of atoms as long as the isostere possesses the same total orvalence electrons in the same arrangement as does a pyrimidin-1-ylgroup. For example, well known isosteric pairs of molecules include thepair carbon monoxide and atmospheric nitrogen and the pair cyanide ionand acetylide ion. Heterocyclic isosteres of a pyrimidin-1-yl groupinclude, but are not limited to, compounds of the formula: ##STR12##wherein V is O or S;

Q is --OH, --SH, alkoxy, thioalkoxy, halogen, ##STR13## wherein m is 1to 5, --NR₁ R₂ wherein R₁ and R₂ are as defined above, --NHC(O)R₃wherein R₃ is as defined above; and

T is hydrogen, C₁ to C₁₀ alkyl, 2-haloethyl, halomethyl, difluoromethyl,trifluoromethyl, halogen, cyano, nitro, vinyl, 2-halovinyl, alkynyl,hydroxmethyl, formyl, azidomethyl, 2-hydroxyethyl, --NR₁ R₂ wherein R₁and R₂ are as defined above, --NHOH, --SH, propenyl,3,3,3-trifluoropropenyl, 2-(alkoxycarbonyl)ethenyl, 2-cyanoethenyl,##STR14## wherein m is 1 to 5, or --CH₂ NR₁ R₂ wherein R₁ and R₂ are asdefined above.

The compounds of the present invention may be prepared by variousmethods disclosed in Schemes I to XXV.

According to one method (Scheme I), the adduct of diethyl fumarate andallene (the compound of Formula XIII (Cripps, et al., J. Am. Chem. Soc.1959, 81, 2723-2728)) is reduced with a reducing agent such as lithiumaluminum hydride and then treated with ozone and then dimethyl sulfideto afford the ketone diol of Formula XIV. This compound is, in turn,condensed with O-methyl hydroxylamine and then a suitable reagent toprotect the hydroxyl groups, such as t-butyldimethylsilyl chloride(TBS-Cl) to afford the oxime of Formula XV. This compound is, in turn,treated with a reducing agent, preferably Na(BH₃)O₂ CCF₃ intetrahydrofuran (THF) to afford the amine of Formula XVI. This compoundis, in turn, treated with a reagent such as chlorotrimethylsilane inmethanol to remove the TBS protecting groups and afford the aminehydrochloride of Formula XVII. As demonstrated in subsequent Schemes,compounds of Formula XVI and XVII are key intermediates used in thesynthesis of purines, pyrimidines, and their heterocyclic isosteres.

According to one method (Scheme II), the compound of Formula XVII iscondensed with 2-amino-4,6-dichloropyrimidine in the presence of atertiary amine base to afford the pyrimidine of Formula XIX. Thiscompound, is in turn, converted to the pyrimidine of Formula XXI by wayof azo coupling with 4-chlorobenzenediazonium chloride and reductionwith zinc in acetic acid. The purine of Formula XXII is then prepared bytreatment of the pyrimidine of Formula XXI with triethyl orthoformateand acid, or preferably, diethoxymethyl acetate, followed by ammonia inmethanol and then a protic acid in methanol. Compounds of Formula XXIII,are in turn, obtained by treating the compound of Formula XXII withvarious nucleophiles. For instance, treatment of the compound of FormulaXXII with aqueous acid affords the compound of Formula XXIII in whichJ=OH; alternatively, treatment of the compound of Formula XXII withammonia in an alcoholic solvent affords the compound of Formula XXIII inwhich J=NH₂ ; alternatively, treatment of the compound of Formula XXII(or its diacetate) with hydrogen in the presence of a noble metalcatalyst (and then NH₃ in MeOH for the diacetate) affords the compoundof Formula XXIII in which J=H.

According to one method (Scheme III), the compound of Formula XXIII inwhich J=OH is prepared by the condensation of the compound of FormulaXVI with the compound of Formula XXIV in a suitable solvent such as DMFin the presence of a tertiary amine base to afford the compound ofFormula XXV. Reduction of this compound by zinc in formic acid, followedby removal of the zinc (or reduction by hydrogen over a noble metalcatalyst in formic acid), heating in formic acid, removal of formicacid, treatment with aqueous ammonia, and crystallization from wateraffords the compound of Formula XXIII.

According to one method (Scheme IV), the compound of Formula XVI iscondensed with triemthylsilyl isocyanate and then treated with silicagel to afford the compound of Formula XXVI. This compound is in turn,condensed with either (E)-3-methoxy-2-methylpropenoyl chloride or (E)-3-ethoxyacryloyl chloride to afford compounds of Formula XXVII. Thesecompounds are, in turn, treated with either aqueous acid or base tocause cyclization to compounds of the Formula XXVIII. The compounds are,in turn, treated at elevated temperature with hexamethy disilazane andformamide to afford compounds of the Formula XXIX.

According to one method (Scheme V), the compound of Formula XVII iscondensed with 5-amino-4,6-dichloropyrimidine (the compound of FormulaXXX) in the presence of a tertiary amine base to afford the pyrimidineof Formula XXXI. This compound is, in turn, treated withtriethylorthoformate and acid or preferably diethoxymethyl acetatefollowed by ammonia in methanol followed by a protic acid in methanol toafford the pyrimidine of Formula XXXII. This compound is, in turn,converted into purines of the Formula XXXIII by the methods outlinedabove in Scheme II for the conversion of purines of the Formula XXIIinto purines of the Formula XXIII.

According to one method (Scheme VI), the compound of Formula XXXIV(Cripps, et al. J. Am. Chem. Soc. 1959, 81, 2723-2728) is treated withdiphenylphosphoryl azide, triethylamine, and an alcohol such as benzylalcohol or t-butyl alcohol to afford compounds of the Formula XXXV inwhich R₁₅ is benzyl or t-butyl. These compounds are in turn hydroboratedwith BH₃ in THF to afford the compound of Formula XXXVI in which E is H,or hydroxylated with potassium permanganate to afford the compound ofFormula XXXVII in which E is OH. Compounds of the Formula XXXVII are, inturn, converted into compounds of the Formula I by the methods analogousto those outlined above for the preparation of compounds of the FormulasXXII, XXIII, XXVIII, XXIX, XXXII, and XXXIII.

According to one method (Scheme VI), the compound of Formula XXXVIII(Caserio, et al. J. Am. Chem Soc. 1958, 80, 5507-5513) is converted bythe action of di-t-butyl dicarbonate to the compound of Formula XXXIX inwhich R₁₅ is t-butyl. This compound is, in turn, treated with ozone andthen dimethylsulfide followed by hydroxylamine and hydrogen over a noblemetal catalyst to afford the compound of the Formula XL in which R₁₅ ist-butyl. This compound is, in turn, converted into compounds of theFormula I by methods analogous to those used in the preparation ofcompounds of the Formula XXXIII, but removing the t-butyloxycarbonylprotecting group with 4.5M HC1 in dioxane.

According to one method (Scheme VII), compounds of the Formula XLI areprotected at the 3'-hydroxymethyl group to afford compounds of theFormula XLII, in which TBS may represent any protecting group. In thepreferred example, compounds of the Formula XLI are treated witht-butyldimethylsilyl chloride (TBS-Cl) to afford compounds of theFormula XLII in which TBS represents t-butyldimethylsilyl. Compounds ofthe Formula XLII are in turn treated with methanesulfonyl chloride toafford compounds of the Formula XLIII. These compounds are in turntreated with various nucleophiles and then deprotected. In the preferredexample, in which TBS is t-butyldimethylsilyl, the protecting group isremoved by trimethylsilyl chloride in methanol. When the nucleophile isazide, X in the compound of Formula XLIV is azido; when the nucleophileis a halide, X is halo; when the nucleophile is cyanide, X is cyano.Treatment of the compound of the Formula XLIV when X is B withtri-n-butyl tin hydride affords the compound of the Formula XLIV inwhich X is H.

According to one method (Scheme VIII), compounds of the Formula XLI aretreated with various acid chlorides or acid anhydrides to affordcompounds of the Formulas XLV, XLVI, and XLVII.

According to one method (Scheme IX), the optically pure compound ofFormula XLVIII (R is C₁ -C₄ alkyl) is reduced with a reducing agent suchas di-iso-butylaluminum hydride to afford the diol of Formula XLIX. Thediol is treated with a suitable reagent to protect the hydroxyl groups,such as t-butyldimethylsilyl chloride, and then treated with anoxidizing agent, such as meta-chloroperoxybenzoic acid (mCPBA) to affordthe epoxide of Formula LI. This cyclopropyl compound is expanded to thecyclobutanone of Formula LII by treatment with lithium iodide and theketone is, in turn, converted to the O-methyl oxime ether of the FormulaLIII by treatment with O-methyl hydroxylamine in the presence of a basesuch as pyridine. The oxime ether is reduced with a reducing agent, suchas sodium borohydride, in the presence of an equivalent amount oftrifluoroacetic acid to afford the amine of Formula LIV. As demonstratedin subsequent Schemes, the compound of Formula LIV is a key intermediateused in the synthesis of compounds of the invention.

According to one method (Scheme X), allene is condensed with a fumaratediester of the Formula LVI (R is C₁ -C₄ alkyl) to afford the compound ofFormula XLVIII. This compound is reduced with a reducing agent, such aslithium aluminum hydride, to the diol of Formula XLIX, which is, inturn, treated with a suitable reagent to protect the hydroxyl groups,such as t-butydimethylsilyl chloride, to afford the compound of FormulaL. This compound, in turn, is treated with ozone, followed by dimethylsulfide, to give the ketone of Formula LII which is, in turn,selectively reduced with a reducing agent such as L-selectride to affordthe alcohol of Formula LVII. The protecting groups are removed bytreatment with a reagent such as chlorotrimethylsilane to afford thetriol of Formula LVIII which is treated with benzaldehyde dimethylacetal to afford the compound of Formula LIX. The cyclic benzaldehydeacetal of Formula LIX is converted to the compound of Formula LX bytreatment with a brominating agent, such as N-bromosuccinimide, in thepresence of a base such as barium carbonate. This compound is, in turn,treated with tetra-n-butylammonium fluoride to generate the compound ofFormula LXI. The compound of Formula LXI is converted to the ketone ofFormula LXII by treatment with ozone, followed by dimethyl sulfide. Thiscompound is, in turn, reduced with a reducing agent, preferably, (AcO)₃BHNa, generated in situ from glacial acetic acid and sodium borohydride,to afford the diol of Formula LXIII, which, in turn, is treated with asuitable reagent to protect the hydroxyl groups, such ast-butyldiphenylsilyl chloride to afford the compound of Formula LXIV.This compound is then converted to the compound of Formula LXV bytreatment with a reducing agent, such as lithium triethylborohydride.The alcohol is derivatized with methane sulfonyl chloride and theresulting mesylate treated with an azide salt, such as lithium azide, toafford the compound of Formula LXVI. The azide of Formula LXVI is thenreduced by hydrogenation in the presence of a catalyst such as palladiumon carbon to afford the amino compound of the Formula LXVII. Asdemonstrated in subsequent Schemes, the compound of Formula LXVII is akey intermediate used in the synthesis of compounds of the invention.

According to one method (Scheme XI), 1,3-dibromo-2,2-dimethoxypropane iscondensed with a malonate diester (R is C₁ -C₄ alkyl) of the FormulaLXIX to afford the cyclobutane dicarboxylate derivative of Formula LXX.This compound, in turn, is reduced with a reducing agent, such aslithium aluminum hydride, to afford the diol of Formula LXXI which is,in turn, hydrolyzed with a mineral acid, such as hydrochloric acid, toafford the ketone of Formula LXXII. The ketone is then converted to theO-methyl oxime ether by treatment with O-methyl hydroxylamine in thepresence of an amine base such as pyridine, followed by treatment with asuitable reagent to protect the hydroxyl groups, such ast-butydimethylsilyl chloride, to afford the compound of Formula LXXIV.The oxime ether is reduced with a reducing agent, such as sodiumborohydride, in the presence of an equivalent amount of trifluoroaceticacid to afford the amine of Formula LXXV. As demonstrated in subsequentSchemes, the compound of Formula LXXV is a key intermediate used in thesynthesis of compounds of the invention.

According to one method (Scheme XII), methylenecyclobutyl nitrile(LXXVI) is hydrolyzed in aqueous base to the acid of Formula XXXIV,which is then converted to the Cbz-protected amino compound of FormulaXXXV by treatment with diphenylphosphonyl azide, in the presence of atertiary amine base, followed by treatment with benzyl alcohol. Thiscompound is then converted to the keto derivative of Formula LXXVII bytreatment with ozone and dimethyl sulfide. This compound, in turn,reduced with a reducing agent such as K-selectride to the correspondingalcohol of Formula LXXVIII which is, in turn, treated with a suitablereagent to protect the hydroxyl groups, such as t-butydimethylsilylchloride, to afford the compound of Formula LXXIX. This compound is thenconverted to the amino compound of Formula LXXX by hydrogenolysis in thepresence of a catalyst, such as 10% palladium on carbon. As demonstratedin subsequent Schemes, the compound of Formula LXXX is a keyintermediate used in the synthesis of compounds of the invention.

According to one method (Scheme XIII), the compound of Formula LXXXI isreduced with a reducing agent, such as diborane to the triol of FormulaLXXXII. This compound is then treated with a suitable reagent to protectthe primary hydroxyl groups, such as t-butydimethylsilyl chloride,followed by treatment of the secondary hydroxyl group withmethanesulfonyl chloride, to afford the compound of Formula LXXXIV. Themesylate (LXXXIV) is treated with lithium azide to afford the azidocompound of Formula LXXXV, which is, in turn, reduced by catalytichydrogenation to afford the amino compound of the Formula LXXXVI. Asdemonstrated in subsequent Schemes, the compound of Formula LXXXVI is akey intermediate used in the synthesis of compounds of the invention.

According to one method (Scheme XIV), the compounds of FormulasLXXXIX-XCIII are prepared by the condensation of the compound of FormulaXXIV with an amino compound, such as one of the compounds of FormulasLIV, LXVII, LXXV, LXXX or LXXXVI, in a suitable solvent, such as DMF, inthe presence of a tertiary amine base to afford the compounds of FormulaLXXXVII. Reduction of the nitro group with zinc in formic acid or bycatalytic hydrogenation, followed by heating in formic acid and thentreatment with NH₄ OH affords the compounds of Formulas LXXXIX-XCIII.The compound of Formula XCII is then converted to the compound ofFormula XCIV by treatment with diethylphosphonomethyl triflate in thepresence of a suitable base, such as sodium hydride, followed bycleavage of the phosphonate ester.

According to one Scheme (Scheme XV), an amino compound, for example oneof the compounds of Formulas LIV, LXVII, LXXV, LXXX or LXXXVI, iscondensed with 5-amino-4,6-dichloropyrimidine (XXX) in the presence of atertiary amine base to afford a pyrimidine of Formula XCV. Thiscompound, in turn, is converted to a 6-chloropurine derivative ofFormula XCVI by treatment with dimethoxymethyl acetate. This compound,in turn, is treated with ammonia in methanol to afford the compounds ofFormula XCVII. The hydroxyl protecting groups are removed by treatmentof the compound of Formula XCVII with a reagent such aschlorotrimethylsilane/methanol to afford the purine compounds ofFormulas XCVIII-CII. The compound of Formula CI is then converted to thecompound of Formula CIII by treatment with diethylphosphonomethyltriflate in the presence of a suitable base, such as sodium hydride,followed by cleavage of the phosphonate ester.

According to one Scheme (Scheme XVI) an amine, such as one of thecompounds of Formulas LIV, LXVII, LXXV, LXXX or LXXXVI, is condensedwith trimethylsilylisocyanate and then treated with silica gel to affordthe compounds of Formula CIV. This compound is in turn, condensed witheither (E)-3-methoxy-2-methylpropenoyl chloride or (E)-3-ethoxyacryloylchloride to afford compounds of Formula CV. These compounds are, inturn, treated with either aqueous acid or base to cause cyclization tocompounds of the Formula CVI-CXV. The compounds of the Formula CVI-CXVare, in turn, treated at elevated temperature with hexamethyldisilazaneand formamide to afford compounds of the Formulas CXVII-CXXVI. Thecompounds of Formula CIX and CXIV are then converted to the compounds ofFormula CXVI by treatment with diethylphosphonomethyl triflate in thepresence of a suitable base, such as sodium hydride, followed bycleavage of the phosphonate ester to afford the compounds of FormulaCXVI. The compounds of Formula CXX and CXXV are converted to thecompounds of Formula CXXVII by treatment with diethylphosphonomethyltriflate in the presence of a suitable base, such as sodium hydride,followed by cleavage of the phosphonate ester to afford the compounds ofFormula CXXVII.

According to one Scheme (Scheme XVII), in which A is as defined forFormula I, the compound of Formula CXXVIII is dehydrobrominated bytreatment with a base, such as potassium hydroxide, in a suitablesolvent, such as toluene, to the unsaturated cyclobutanecarboxylic acidof Formula CXXIX, which is converted to the corresponding methyl ester(CXXX in which R is methyl) with diazomethane. The unsaturated ester ofFormula CXXX is then condensed with a pyrimidine or purine base, or aheterocyclic isostere thereof, in a Michael addition to afford thecompound of Formula CXXXI. This compound, in turn, is reduced bytreatment with a reducing agent, such as lithium borohydride or lithiumaluminum hydride, to the hydroxymethyl derivative of Formula CXXXII.

According to one Scheme (Scheme XVIII), in which A is as defined forFormula I, diethyl ketene acetal (CXXXIII) and a propiolate ester (R isC₁ -C₄ alkyl) of Formula CXXXIV are condensed to afford the cyclobutylcompound of Formula CXXXV. This compound is then condensed with apyrimidine or purine base, or a heterocyclic isostere thereof, in aMichael addition to afford the compound of Formula CXXXVI. This compoundis further converted to the hydroxymethyl compound of Formula CXXXVII byreduction with a reducing agent such as lithium aluminum hydride. Thediethyl ketal is hydrolyzed to the ketone of Formula CXXXVIII in acidicsolution and the ketone is subsequently reduced with a reducing agent,such as sodium borohydride, to afford the compound of Formula CXXXIX.This compound is then treated with a suitable reagent to protect theprimary hydroxyl group, such as t-butydimethylsilyl chloride to affordthe compound of Formula CXXXX. This compound is converted to thecompound of Formula CXXXXI by treatment with diethylphosphonomethyltriflate in the presence of a suitable base, such as sodium hydride,followed by removal of the hydroxyl protecting groups by treatment witha reagent such as bromotrimethylsilane to afford the compound of FormulaCXXXXI.

According to one method (Scheme XIX), the compounds of Formula XLI, inwhich A is guanine or adenine, are treated with Aldrithiol-2 in thepresence of tributylphosphine to afford the compounds of FormulaCXXXXII. These compounds, in turn, are reduced with sodium in liquidammonia to afford the compounds of Formula CXXXXIII.

According to one method (Scheme XX), a chloropyrimidine of the FormulaCXXXXIV is condensed with an aminocyclobutane, such as the compound ofFormula XVII in the presence of a tertiary amine base at ambient orelevated temperature to afford the compounds of Formula CXXXXV. Thesecompounds are, in turn, cyclized in acidic solution to afford compoundsof the Formula CXXXXVI. These compounds are then treated with a suitablereagent to protect the primary hydroxyl groups, such as acetic anhydridein the presence of a tertiary amine base to afford the compounds of theFormula CXXXXVII. These compounds are, in turn, brominated with asuitable brominating agent, such as N-bromoacetamide to afford thecompounds of Formula CXXXXVIII. The removal of the hydroxyl protectinggroups by treatment with a basic reagent such as ammonia in methanolaffords the compounds of Formula CXXXIX

According to one method (Scheme XXI A), a vinyl thioether of the Formula(CL), wherein R²⁷ is alkyl, phenyl or substituted phenyl, is condensedwith a fumaric or maleic acid diester of the Formula CLI, wherein R²⁸and R²⁹ are independently selected from loweralkyl, aryl and arylalkyl,in the presence of a Lewis acid catalyst such as aluminum trichloride orethylaluminum dichloride, in a suitable solvent at a temperature in therange of -78° C. to 110° C., to give a cyclobutyl sulfide of the FormulaCLII. Preferably, phenyl vinyl sulfide is condensed with dimethylfumarate in the presence of ethylaluminum dichloride in methylenechloride at ambient emperature. Oxidation of a sulfide of the FormulaCLII with an oxidant such as 3-chloroperoxybenzoic acid (mCPBA), otherperacids, hydrogen peroxide in acetic acid or oxone® (a commerciallyavailable mixture of sulfuric acid potassium salt and potassium hydrogenperoxymonosulfate), gives a sulfone diester of the Formula CLIII.

According to one method (Scheme XXI B), a vinyl thioether of the FormulaCL, wherein R²⁷ is alkyl, phenyl or substituted phenyl, is condensedwith maleic anhydride (CLIV), in the presence of a Lewis acid catalystsuch as aluminum trichloride or ethylaluminum dichloride, in a suitablesolvent at a temperature in the range -78° C. to 110° C., to give ananhydride of the Formula CLV. Preferably, phenyl vinyl sulfide iscondensed with maleic anhydride in the presence of ethylaluminumdichloride in methylene chloride at ambient temperature. Treatment ofthe compound of Formula CLV with an alcohol such as methanol underacidic conditions yields a diester of Formula CLII. Oxidation of thesulfide of the Formula CLII with an oxidant such as mCPBA, otherperacids, hydrogen peroxide in acetic acid or oxone®, gives a sulfonediester of the Formula CLIII. Alternately, oxidation of a sulfide of theFormula CLV with an oxidant such as mCPBA, hydrogen peroxide in aceticacid, other peracids or OXONE gives a sulfone diester of the FormulaCLVI. Treatment of a compound of Formula CLVI with an alcohol such asmethanol under acidic conditions yields a diester of the Formula CLIII.

According to one method (Scheme XXII) a sulfone of the Formula CLIII iscoupled with a nucleophile of the Formula CLVII, wherein A is apurin-9-yl group or a heterocyclic isostere of a purin-9-yl group asdefined for Formula I, under conditions suitable to effect eliminationof the elements of HSO₂ R²⁷ to afford the compound of the Formula CLIX,for example at a sufficiently elevated temperature or in the presence ofa suitable base such as sodium hydride, potassium hydride,diazabicycloundecene, diazabicyclononane or diazabicyclooctane, insolvents such as DMF or DMSO at ambient or elevated temperature to yieldcompounds of the Formula CLIX, presumably via the conjugate addition ofcompounds of the Formula CLVII to the double bond in the intermediate ofthe Formula CLVIII. Optionally, treatment of the reaction mixturecontaining product CLIX with a suitable base in a suitable solvent,preferably with sodium methoxide in methanol, increases the proportionof the preferred isomer of compounds of the Formula CLIX. Reduction ofcompounds of the Formula CLIX with a reducing agent such as lithiumaluminum hydride or sodium borohydride-methanol yields compounds of theFormula XLI. In certain cases, treatment of compounds of the Formula XLIwith aqueous acids such as hydrochloric acid, with aqueous bases such assodium hydroxide or with ammonia yields other compounds of Formula CLIX,wherein the group A has been modified by this treatment.

According to one method (Scheme XXIII A), a mixture of a vinyl halide ofthe Formula CLX, wherein X is selected from Cl, Br, and I, and maleicanhydride in a suitable solvent is irradiated with ultraviolet light inthe presence of a sensitizer to yield a compound of the Formula CLXI.Preferably, vinyl bromide and maleic anhydride in ethyl acetate areirradiated with a medium pressure mercury vapor lamp in the presence ofacetophenone to yield a compound of the Formula CLXI with X=Br.Treatment of a compound of the Formula CLXI with an alcohol such asmethanol under acidic conditions yields a diester of the Formula CLXII,wherein R²⁸ and R²⁹ are independently selected from loweralkyl, aryl andarylalkyl.

According to one method (Scheme XXIII B), a cyclobutyl sulfide of theFormula CLII, wherein R²⁸ and R²⁹ are independently selected fromloweralkyl, aryl and arylalkyl, is treated with one equivalent of anoxidant such as mCPBA, other peracids, hydrogen peroxide in acetic acidor oxone® to give a sulfoxide diester Of the Formula CLXIII.

According to one method (Scheme XXIII C), compounds of Formula XLXIV,prepared as described by Cripps, et al. in J Am Chem Soc. 81, 2723-8(1959) utilizing, in addition to diethyl fumarate, other esters offumaric acid, wherein R²⁸ and R²⁹ are independently selected fromloweralkyl, aryl and arylalkyl, are treated with ozone and then withdimethyl sulfide to afford the ketone diesters of the formula CLXV.Treatment of these compounds with a reducing agent such as sodiumborohydride, sodium cyanoborohydride, or diisobutylaluminum hydride in asuitable solvent yields compounds of the Formula CLXVI. Alcohols of theFormula CLXVI can be activated toward elimation by methods well known inthe art, for example by treatment with methanesulfonyl chloride orparatoluenesulfonyl chloride and triethylamine, or with acetic anhydridein pyridine, to yield compounds of the Formula CLXVII.

According to one method (Scheme XXIV), a cyclobutane of the FormulaCLXII, wherein R²⁸ and R²⁹ are independently selected from loweralkyl,aryl and arylalkyl; and X is a leaving group such as Cl, Br, I, alkylsulfoxide, acetate, or an aryl sulfonate or alkyl sulfonate well knownin the art (e.g., OTs or OMs), is coupled with a nucleophile of theFormula CLVII, wherein A is a purin-9-yl group or a heterocyclicisostere of a purin-9-yl group as defined for Formula I, underconditions suitable to effect elimination of the elements of HX toafford the compound of the Formula CLIX, for example at a sufficientlyelevated temperature or in the presence of a base such as sodiumhydride, potassium hydride, diazabicycloundecene, diazabi-cyclononane,or diazabicyclooctane in solvents such as dimethylformamide ordimethylsulfoxide at ambient or elevated temperature, to yield compoundsof the Formula CLIX, presumably via the conjugate addition of compoundsof the Formula CLVII to the double bond in the intermediate of theFormula CLVIII. Reduction of compounds of the Formula CLIX with areducing agent such as lithium aluminum hydride or sodiumborohydride-methanol yields compounds of the Formula XLI.

According to one method (Scheme XXV), a cyclobutane of the Formula CLXI,wherein X is a leaving group such as Cl, Br, I, alkyl sulfoxide, arylsulfoxide, alkyl sulfone, aryl sulfone, acetate, or an aryl sulfonate oralkyl sulfonate well known in the art (e.g., OTs or OMs) is coupled witha nucleophile of the Formula CLVII, wherein A is a purin-9-yl group or aheterocyclic isostere of a purin-9-yl group as defined for Formula I,under conditions suitable to effect elimination of the elements of HX toafford the compound of the Formula CLXIX, for example at a sufficientlyelevated temperature or in the presence of a base such as sodiumhydride, potassium hydride, diazabicycloundecene, diazabicyclononane, ordiazabicyclooctane in solvents such as dimethylformamide ordimethylsulfoxide at ambient or elevated temperature, to yield compoundsof the Formula CLXIX (wherein R²⁸ and R²⁹ are independently selectedloweralkyl, aryl and arylalkyl), presumably via the conjugate additionof compounds of the Formula CLVII to the double bond in the intermediateof the Formula CLXVIII. Treatment of a compound of the Formula CLXIXwith alcohol under acidic conditions yields a diester of the FormulaXLIX. Optionally, treatment of the reaction mixture with a suitable basein a suitable solvent, preferably with sodium methoxide in methanol,increases the proportion of the preferred isomer of compounds of theFormula XLIX. Reduction of compounds of the Formula XLIX with a reducingagent such as lithium aluminum hydride or sodium borohydride-methanolyields compounds of the Formula XLI. In certain cases, treatment ofcompounds of the Formula XLI with aqueous acids such as hydrochloricacid, with aqueous bases such as sodium hydroxide, or with ammoniayields other compounds of the Formula XLI wherein the group A has beenmodified by this treatment. ##STR15##

Useful intermediates for the preparation of compounds of the inventioninclude compounds of the formula: ##STR16## wherein E is hydrogen, --CH₂OH, --CH₂ OR₁₁, --OH or --OR₁₁ ; and

G and D are independently selected from hydrogen, C₁ to C₁₀ alkyl, --OH,--OR₁₁, --CH₂ OH, --CH₂ OR₁₁, --CH₂ OC(O)R₂₁ wherein R₂₁ is as definedabove, --CH₂ OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as definedabove, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H, --CH₂CN, --CH₂ N₃, --CH₂ NR₁₂ R₂, --CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₁₁,--CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as defined above, --CH₂ OPO₃H₂, --CH₂ CH₂ PO₃ H₂, --CH₂ PO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃wherein R₁₂ is hydrogen, C₁ to C₁₀ alkyl, R₃ is hydrogen, C₁ to C₁₀alkyl, carboxyalkyl or aminoalkyl, R₁₁ is C₁ to C₆ alkyl or a hydroxyprotecting group, and R₁₃ is hydrogen or an N-protecting group; with theproviso that when E is --OH then D is not --OH.

Other useful intermediates for the preparation of the compounds of theinvention include compounds of the formula: ##STR17## wherein E ishydrogen, --CH₂ OH, --CH₂ OR₁₁, --OH or --OR₁₁ ;

G and D are independently selected from hydrogen, C₁ to C₁₀ alkyl, --OH,--OR₁₁, --CH₂ OH, --CH₂ OR₁₁, --CH₂ OC(O)R₂₁ wherein R₂₁ is as definedabove, --CH₂ OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as definedabove, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H, --CH₂CN, --CN₂ N₃, --CH₂ NR₁₂ R₂, --CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₁₁,--CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as defined above, --CH₂ OPO₃H₂, --CH₂ CH₂ PO₃ H₂, --CH₂ PO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃wherein R₁₂ is hydrogen, C₁ to C₁₀ alkyl or an N-protecting group, R₂ ishydrogen or C₁ to C₁₀ alkyl, R₃ is hydrogen, C₁ to C₁₀ alkyl,carboxylakyl or aminoalkyl, R₁₁ is C₁ to C₆ alkyl or a hydroxyprotecting group, and R₁₃ is an N-protecting group;

R₁₆ is hydrogen, --NH₂ or --OH;

R₁₇ is --OH or halogen; and

R₁₈ is --NO₂ or --NH₂ ; with the proviso that when E is --OH then D isnot --OH.

Other useful intermediates for the preparation of the compounds of theinvention include compounds of the formula: ##STR18## wherein E ishydrogen, --CH₂ OH, --CH₂ OR₁₁, --OH or --OR₁₁ ;

G and D are independently selected from hydrogen, C₁ to C₁₀ alkyl, --OH,--OR₁₁, --CH₂ OH, --CH₂ R₁₁, --CH₂ OC(O)R₂₁ wherein R₂₁ is as definedabove, --CH₂ OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as definedabove, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H, --CH₂CN, --CH₂ N₃, --CH₂ NR₁₂ R₂, --CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₁₁,--CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as defined above, --CH₂ OPO₃H₂, --CH₂ CH₂ PO₃ H₂, --CH₂ PO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃wherein R₁₂ is hydrogen, C₁ to C₁₀ alkyl or an N-protecting group, R₂ ishydrogen or C₁ to C₁₀ alkyl, R₃ is hydrogen, C₁ to C₁₀ alkyl,carboxyalkyl or aminoalkyl, R₁₁ is C₁ to C₆ alkyl or a hydroxyprotecting group, and R₁₃ is an N-protecting group; and

R₁₉ is C₁ to C₆ alkyl; with the proviso that when E is --OH then D isnot --OH.

Other useful intermediates for the preparation of the compounds of theinvention include compounds of the formula: ##STR19## wherein E ishydrogen, --CH₂ OH, --CH₂ OR₁₁, --OH or --OR₁₁ ;

G and D are independently selected from hydrogen, C₁ to C₁₀ alkyl, --OH,--OR₁₁, --CH₂ OH, --CH₂ OR₁₁, --CH₂ OC(O)R₂₁ wherein R₂₁ is as definedabove, --CH₂ OC(O)CH(R₂₂ (NHR₂₃) wherein R₂₂ and R₂₃ are as definedabove, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H, --CH₂CN, --CH₂ N₃, --CH₂ NR₁₂ R₂, --CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₁₁,--CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂OC(O)CH(R₂₂)(NHR₂₃) wherein R₂₂ and R₂₃ are as defined above, --CH₂ OPO₃H₂, --CH₂ CH₂ PO₃ H₂, --CH₂ PO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃wherein R₁₂ is hydrogen, C₁ to C₁₀ alkyl or an N-protecting group, R₂ ishydrogen or C₁ to C₁₀ alkyl, R₃ is hydrogen, C₁ to C₁₀ alkyl,carboxyalkyl or aminoalkyl, R₁₁ is C₁ to C₆ alkyl or a hydroxyprotecting group, and R₁₃ is an N-protecting group; and

T is hydrogen, C₁ to C₁₀ alkyl, 2-haloethyl, halomethyl, difluoromethyl,trifluoromethyl, halogen, cyano, nitro, vinyl, 2-halovinyl, alkynyl,hydroxmethyl, formyl, azidomethyl, 2-hydroxyethyl, --NR₁₂ R₂ wherein R₁₂and R₂ are as defined above, --NHOH, --SH, propenyl,3,3,3-trifluoropropenyl, 2-(alkoxycarbonyl)ethenyl, 2-cyanoethenyl,##STR20## wherein m is 1 to 5, or --CH₂ NR₁₂ R₂ wherein R₁₂ and R₂ areas defined above; with the proviso that when E is --OH then D is not--OH.

The term "N-protecting group" as used herein refers to those groupsintended to protect nitrogen atoms against undesirable reactions duringsynthetic procedures and includes, but is not limited to, acyl, acetyl,pivaloyl, t-butylacetyl, trichloroethoxycarbonyl, t-butyloxycarbonyl(Boc), benzyloxycarbonyl (Cbz) or benzoyl groups or other nitrogenprotecting groups known to those skilled in organic synthesis such asthose disclosed in Greene, "Protective Groups in Organic Synthesis", pp.218-287, (J. Wiley & Sons, 1981).

The term "hydroxy protecting group" as used herein refers to thosegroups intended to protect a hydroxy group against undesirable reactionsduring synthetic procedures and includes, but is not limited to,substituted methyl ethers, for example, methoxymethyl, benzyloxymethyl,2-methoxyethoxymethyl, 2-(trimethylsilyl)ethoxymethyl andtetrahydropyranyl; substituted ethyl ethers, for example,2,2,2-trichloroethyl, t-butyl, benzyl and triphenylmethyl; silyl ethers,for example, trimethylsilyl, t-butyldimethylsilyl andt-butyldiphenylsilyl; acyl groups such as acetyl and benzoyl; sulfonatessuch as mesylate and tosylate; or other hydroxy protecting groups knownto those skilled in organic synthesis such as those disclosed in Greene,"Protective Groups in Organic Synthesis", pp. 10-71, (J. Wiley & Sons,1981).

The following examples will serve to further illustrate preparation ofthe novel compounds of the invention.

EXAMPLE 1 9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine Step A:1,2-bis(hydroxymethyl)-3-methylenecyclobutane

To a stirred solution of 40.0 g (0.188 mol) of1,2-bis(ethoxycarbonyl-3-methylenecyclobutane (Cripps, H. N.; Williams,J. K.; Sharkey, W. H. J. Am. Chem. Soc. 1959, 81, 2723-2728) in 1.4 L ofdiethyl ether at 0° C. was added 14.4 g (0.379 mol) of lithium aluminumhydride in small portions. After 2 h at 0° C., 14.4 mL of H₂ O, 14.4 mLof 15% aq. NaOH, and then 44.0 mL of H₂ O were added sequentially. Theresulting white solid was removed by filtration and washed thoroughlywith diethyl ether. Concentration of the combined filtrates underreduced pressure afforded 17.1 g (71%) of the title compound as an oil,judged to be 95% pure by NMR: Rf 0.27 (silica gel, 1:1/acetone:hexane);IR (CDCl₃) cm-1; ¹ H NMR (CDCl₃) 1.66 (bs, 1H, OH), 2.24-2.41 (m, 2H),2.44 (bs, 1H, OH), 2.57-2.71 (m, 1H), 2.87-2.96 (m, 1 H), 3.54, 3.58 (2dd, 2H, J=J'=12 Hz, CH₂ O), 3.79, 3.84 (2 dd, 2H, J=10.5 Hz, J'=4.5 Hz,CH₂ O), 4.78, 4.82 (2 ddd, 2H, J=J'=J"=2.5 Hz, C═CH₂); ¹³ C NMR (CDCl₃,CDCl₃ =77.00 ppm)146.21, 105.39, 66.13, 63.74, 51.70, 38.67, 31.86; DCI-NH₃ MS, m/z 129 (M+1)+, 146 (M+NH₄ ⁺)⁺.

Step B: 2,3-Bis(hydroxymethyl)cyclobutanone

Through a solution of 15.0 g (0.117 mol) of the product from Step A ofExample 1 in 872 mL of CH₂ Cl₂ and 218 mL of MeOH at -78° C. was passeda stream of ozone. When a persistent blue color appeared, the solutionwas purged with nitrogen and then treated with 68.0 mL (0.926 mol) ofdimethyl sulfide. After 30 min, the reaction mixture was allowed to warmto room temperature and then concentrated under reduced pressure.Chromatography of the residue on 1 kg of silica gel with a hexane to1:1/hexane:acetone gradient afforded 10.9 g (72%) of the title compoundas an oil, judged to be 90% pure by NMR: Rf 0.17 (silica gel,1:1/hexane:acetone); IR (CDCl₃) 3620, 3430, 2940, 2880, 1775, 1030 cm-1;¹ H NMR (CDCl₃) 1.61, 2.18 (2 bs, OH), 2.54 (ddddd, 1H, J=J'=J"=J'"=J""=8 Hz, J'""=5.5 Hz, H- 3), 2.86, 2.99 (2 ddd, 2H, J=17 Hz, J'=8 Hz,J"=2.5 Hz, H-4) 3.36 (ddddd, 1H, J=J'=J"=8 Hz, J'"=J""=2.5 Hz) 3.74 (dd,1H, J=11 Hz, J'=8 Hz, 3--CH HOH), 3.77-3.90 (m, 2H, 2--CH 2OH) 4.00 (dd,1H, J=11 Hz, J'=5.5 Hz, 3--CHH OH); DCI-NH₃ MS, m/z 131 (M+1)⁺, 148(M+1+NH₃)⁺.

Step C:2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanoneO-Methyl Oxime

To a stirred solution of 10.9 g (83.8 mmol) of the product from Step Bfrom Example 1 in 88 mL of pyridine was added 7.70 g (92.2 mmol) ofO-methylhydroxylamine hydrochloride. After 2 h at room temperature, 117mL of pyridine and 40.0 g (265 mmol) of t-butyldimethylsilyl chloridewas added. After 60 h at room temperature, the reaction mixture wasconcentrated under reduced pressure to a volume of 80 mL, diluted with600 mL of CH₂ Cl₂, washed with 100 mL of H₂ O, dried over MgSO₄, andconcentrated under reduced pressure. Chromatography of the residue on1.25 kg of silica gel with a hexane to 97:3/hexane:acetone gradientafforded 24.9 g (77 %) of the title compound as an oil, judged by NMR tobe a 1.5:1 mixture of geometrical isomers of 95% purity: Rf 0.68 (silicagel, 9:1/hexane:acetone); IR (CHCl₃) 2950, 2930, 2890, 2850, 1675,1470,1460, 1255, 1100, 1040, 1000 cm-1; ¹ H NMR (CDCl₃) 0.04, 0.05 (2 s,6 H, (CH₃)₂ Si), 0.89 (s, 9 H, (CH₃)₃) 2.38-2.64 (m, 2 H), 2.71-2.89 (m,1 H), 3.60-3.74 (m, 2 H), 3.78, 3.82 (2 s, 3 H, OCH₃), 3.78-3.95 (m, 2H); DCI-NH₃ MS, m/z 388 (M+1+NH₃)⁺.

Step D:2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylamine

To a stirred suspension of 1.04 g (27.5 mmol) of NaBH₄ in 50 mL of dryTHF was added dropwise over 5 min 2.12 mL (27.5 mmol) of trifluoroaceticacid. To this mixture was then added a solution of 2.30 g (5.94 mmol) ofthe product from Step C of Example 1 in 16.0 mL of THF. After 16 h atroom temperature, the reaction mixture was diluted with 300 mL of CH₂Cl₂, washed with 100 mL of saturated aqueous NaCl, dried over MgSO₄, andconcentrated under reduced pressure. Chromatography of the residue on200 g of silica gel with a 95:5 to 90:10/CH₂ Cl₂ : MeOH gradientafforded 1.53 g (72%) of the title compound as an oil, judged to be 95%pure by NMR: Rf 0.65 (silica gel, 60:30:1/hexane:acetone:triethylamine);IR (CDCl₃) 3670, 3375, 2955, 2930, 2885, 2855, 1470, 1460, 180, 1360,1255, 1195, 1095, 1060 cm-1; ¹ H NMR (CDCl₃) 0.04 (s, 6 H, (CH₃)₂ Si),0.90 (s, 9 H, (CH₃)₃ C), 1.38 (ddd, 1 H, J=11 Hz, J'=10 Hz, J"= 9 Hz,H-4), 1.80-1.96 (m, 2 H, H-2 and H-3), 2.24 (ddd, 1 H, J=11 Hz, J=8 Hz,J'=7.5 Hz, H- 4), 3.09 (ddd, 1 H, J=9 Hz, J'=J"=8 Hz, H-1), 3.56 (d, 2H, J=4 Hz, CH₂ O), 3.59, 3.69 (2 dd, 2 H, J=10.5 Hz, J'=4 Hz, CH₂ O);DCI-NH₃ MS, m/z 360 (M+1)⁺.

Step E: 2,3-Bis(hydroxymethyl)cyclobutylamine hydrochloride

To a stirred solution of 1.87 g (5.20 mmol) of the product from Step Dof Example 1 in 66 mL of MeOH was added 1.60 mL (12.60 mmol) oftrimethylsilyl chloride. After 1 h at room temperature, the reactionmixture was concentrated under reduced pressure. Evaporation of 3×10 mLof MeOH afforded 742 mg (85 %) of the title compound as an oil, judgedto be 95% pure by NMR: Rf 0.02 (silica gel, CH₂ Cl₂ :MeOH:NH₃); ¹ NMR(CD₃ OD) 1.82 (ddd, 1H, J=11 Hz, J'=J"=9 Hz, H-4), 2.16 (ddddd, 1 H,J=J'=J"=11 Hz, J'"=J""=5.5 Hz, H-3), 2.30-2.40 (m, 2 H, H-2, H-4), 3.49(ddd, 1 H, J=J'=J"=9 Hz, H-1), 3.55, 3.60 (2 dd, 2 H, J=6 Hz, J'=4 Hz,CH₂ O), 3.61, 3.65 (2 dd, 2 H, J=6 Hz, J'=4 Hz, CH₂ O); DCI-NH₃ MS, m/z132 (M+1)⁺.

Step F:3-((2'-Amino-6'-chloro-4'-pyrimidinyl)amino)-1,2-bis(hydroxymethyl)cyclobutane

To a stirred solution of 364 mg (2.18 mmol) of the product from Step Eof Example 1 in 30 mL of EtOH was added 1.51 mL (10.8 mmol) oftriethylamine and 536 mg (3.27 mmol) of 2-amino-4,6-dichloropyrimidine.After 26 h at reflux, the cooled reaction mixture was concentrated underreduced pressure. The residue was then desalted by passage through a 12mL column of Dowex SBR (OH--) resin in 8:2/MeOH:H₂ O and thenconcentrated under reduced pressure. Chromatography of the residue on 40g of silica gel with a 90:10 to 85:15/CH₂ Cl₂ gradient afforded 294 mg(52%) of the title compound, judged to be 95% pure by NMR: Rf 0.29(silica gel, 85:15/CH₂ Cl₂ :MeOH); ¹ H NMR (CD₃ OD) 1.64 (ddd, 1H,J=J'=J"=10 Hz, H-4), 1.90-2.03 (m, 1 H), 2.0-2.15 (m, 1 H), 2.37 (ddd, 1H, J=10 Hz, J'=J"=8 Hz, H-4), 3.52, 3.57 (2 dd, 2 H, J=12 Hz, J'=7 Hz,CH₂ O), 3.59, 3.66 (2dd, 2 H, J=12 Hz, J'=7 Hz, CH₂ O), 3.90-4.02 (bm, 1H, H-1), 5.82 (s, 1 H, H-5'); DCI-NH₃ MS, m/z 259, 261 (M+1)⁺.

Step G: 3-((6'-Chloro2',5'-diamino-4'-pyrimidinyl)amino)-1,2-bis(hydroxymethyl)cyclobutane

To a stirred solution of 294 mg (1.14 mmol) of the product from Step Fof Example 1 and 2.00 g (14.69 mmol) of sodium acetate trihydrate in 5.0mL of acetic acid and 5.0 mL of water was added over 30 min a cold(0°-5° C.) solution of 4-chlorobenzenediazonium chloride (prepared from160 mg (1.25 mmol) of 4-chloroaniline, 1.2 mL of water, 0.35 mL of 12NHCl, and 95 mg (1.51 mmol) of sodium nitrite in 1.2 mL of water). After17 h at room temperature, the yellow precipitate was collected byfiltration, washed with cold water, and dried under vacuum to afford 343mg of the 5'-((4"-chlorophenyl)azo) derivative. Without furtherpurification, this azo compound was dissolved in 7.4 mL of ethanol, 7.4mL of water, and 0.74 mL of acetic acid at 75° C. and treated with 221mg (3.38 mmol) of zinc dust. After 1.5 h, the reaction mixture wasallowed to cool, filtered, the solids washed with ethanol, and thecombined filtrates concentrated under reduced pressure. Chromatographyof the residue on 30 g of silica gel with a CH₂ Cl₂ to 85:15/CH₂ Cl₂:MeOH gradient afforded 176 mg (56%) of the title compound, judged to be95% pure by NMR: Rf 0.29 (silica gel 85:15/CH₂ Cl_(2:) MeOH); ¹ H NMR(CD₃ OD) 1.77 (ddd, 1 H, J=11 Hz, J'=J"=9 Hz, H-4), 1.92-2.04, 2.10-2.20(2 m, 2 H, H-1, H-2), 2.41 (ddd, 1 H, J=11 Hz, J'=8 Hz, J'=7.5 Hz, H-4),3.54, 3.60 (2 dd, 2 H, J=12 Hz, J'=6 Hz, CH₂ O), 3.62, 3.68 (2 dd, 2 H,J=12 Hz, J'=7 Hz, CH₂ O), 4.40 (ddd, 1 H, J=J'=J"=9 Hz, H-3); DCI- NH₃MS, m/z 274 (M+1)⁺.

Step H:3-(2'-Amino-6'-chloro-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane

A solution of 171 mg (0.625 mmol) of the product from Step G of Example1 in 20 mL of diethoxymethyl acetate was heated to reflux. After 22 h,the reaction mixture was allowed to cool and then concentrated underreduced pressure. To a solution of the residue in 30 mL of toluene wasadded 6.5 mg of p-toluenesulfonic acid. After 1.0 h at room temperature,the reaction mixture was concentrated under reduced pressure and thendissolved in 7.0 mL of methanol saturated with NH₃ at 0° C. After 1 h atroom temperature, the reaction mixture was concentrated under reducedpressure and then co evaporated with 3×3 mL of MeOH. To a solution ofthe residue in 12.0 mL of MeOH was added p-toluenesulfonic acid untilthe apparent pH of the reaction mixture was 3, as judged by spotting thereaction mixture on wet pH paper. After 1 h at room temperature, thereaction mixture was neutralized with NH₃ saturated MeOH andconcentrated under reduced pressure. Chromatography of the residue on 25g of silica gel with a 95:5 to 85:15/CH₂ Cl₂ :MeOH gradient afforded 74mg (42%) of the title compound as a white amorphous solid, judged to be95% pure by NMR: Rf 0.30 (silica gel, 85:15/CH₂ Cl₂ MeOH); ¹ H NMR (CD₃OD) 2.17-2.27, 2.85-2.94 (2 m, 2 H, H-1, H-2), 2.89 (ddd, 1 H, J=11 Hz,J'=J"=9 Hz, H-4), 2.55 (ddd, 1 H, J=11 Hz, J'=8 Hz, J"=7 Hz, H-4),3.64-3.74 (m, 4 H, 2 CH₂ O), 4.64 (ddd, 1H, J=J'=9 Hz, J"=8 Hz, H-3),8.19 (s, 1 H, H- 8'); DCI-NH₃ MS, m/z 284, 286 (M+1)⁺.

Step I: 9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

A solution of 70 mg (0.247 mmol) of the product from Step H of Example 1in 7.0 mL of 1N HCl was heated to reflux for 5 h, allowed to cool,concentrated under reduced pressure, and then coevaporated with 3×5 mLof EtOH. The residue was dissolved in 1 mL of H₂ O, neutralized with 15Naqueous NH₃, and then concentrated under reduced pressure. Triturationof the residue with 1 mL of hot EtOH, decantation, and drying undervacuum afforded 59 mg (90%) of the title compound as an amorphous whitesolid: Rf=0.28 (silica gel, 6:4/CH₂ Cl₂ :MeOH); ¹ H NMR (D₂ O, TSP=0.00ppm) 2.17 (ddd, 1 H, J=J'=10 Hz, J"=9 Hz, H-4'), 2.16-2.28, 2.58-2.66,2.69-2.78 (3 m, 3 H, H-4', H-2', H-3'), 3.72, 3.74 (2 d, 4 H, J=6 Hz, 2CH₂ O), 4.51 (ddd, 1 H, J=J'=J"=9 Hz, H-1') 7.97 (s, 1 H, H-8); DCI-NH₃MS, m/z 266 (M+1)⁺.

Alternate Procedure Step J:3-((2'-Amino-3,'4'-dihydro-5'-nitro-4'-oxo-6'-pyrimidinyl)-amino)-1,2-bis((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutane

A solution of 3.00 g (8.34 mmol) of the product from Step D of Example1, 1.84 mL (12.5 mmol) of triethylamine, and 1.58 g (8.29 mmol) of6-chloro-3,4-dihydro-5-nitro-4-oxopyrimidine (Temple, C.; Smith, B. H.;Montgomery, J. A. J. Org. Chem. 1975, 40, 3141-3142) in 20 mL of dry DMFwas heated under nitrogen at 50° C. After 3 h, the cooled reactionmixture was poured into 500 mL of ether, washed with 250 mL of H₂ O,dried over MgSO₄ and then concentrated under reduced pressure.Chromatography of the residue on 300 g of silica gel with a 100:0 to95:5/CH₂ Cl₂ :MeOH gradient afforded 2.40 g (56%) of the title compoundas a yellow glass, judged to be 95% pure by NMR: Rf 0.48 (silica gel,9:1/CH₂ Cl₂ :MeOH); ¹ H NMR (CDCl₃) 0.04, 0.05 (2 s, 12 H, 2 (CH₃)₂ Si),0.90, 0.91 (2 s, 18 H, 2 (CH₃)₃ Si), 1.71 (ddd, 1 H, J=11 Hz, J'=J"=9Hz, H-4), 2.08-2.20 (m, 1 H, H-1), 2.30 (dddd, 1 H, J=J'=9 Hz, J"=J'"= 5Hz, H-2), 2.39 (ddd, 1 H, J=11 Hz, J'=J"=8 Hz, H-4), 3.56-3.74 (m, 4 H,2 CH₂ O), 4.45 (dddd, 1 H, J=J'=9 Hz, J"=J'"=8 Hz, H-3), 1.57, 5.24,8.40 (3 bs, 3 H, NH, NH₂), 9.74 (d, 1 H, J=8 Hz, NH); DCI NH₃ MS, m/z484 (M+H)⁺.

Step K: 9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

A stirred solution of 2.40 g (4.67 mmol) of the product from Step J ofExample 1 in 190 mL of 96% formic acid (remainder H₂ O) was degassedwith argon and then treated with 12.0 g (184 mmol) of zinc dust (325mesh) at room temperature. After 1.5 h at room temperature, the reactionmixture was filtered through a medium glass frit, concentrated to 25 mL,transferred to a steel bomb, degassed with a stream of argon, sealed,and then heated with stirring at 180° C. A small amount of whiteprecipitate quickly dissolved and the reaction mixture became paleyellow. After 2.5 h, the reaction mixture was cooled in an ice bath,carefully vented, and then concentrated under reduced pressure. Residualformic acid was removed by coevaporation with H₂ O until the pH was 4.The resulting solid was suspended in 50 mL of H₂ O, removed byfiltration, dried in vacuo to a weight of 1.1 g, dissolved in 20 mL of15 M NH₄ OH, concentrated under reduced pressure, and then coevaporatedwith 10 ml of H₂ O to afford 940 mg of a pale yellow solid. Thismaterial was suspended in 15 mL of EtOH, heated to 80° C., cooled to 0°C., and then filtered to afford 347 mg of a pale yellow solid. Themother liquor was concentrated under reduced pressure, and the gummyyellow residue was crystallized from H₂ O and washed with acetone toafford 353 mg of an off white solid. This material was combined with theprevious crop, dissolved in 30 mL of H₂ O at 60° C., treated with 550 mgof Darco G-60 charcoal for 2 min, and filtered through a 0.45 micronfilter. The charcoal was washed with 3×10 mL of H₂ O at 60° C. and thecombined filtrates were concentrated under reduced pressure,crystallized from H₂ O (ca. 50 mg/mL), washed with acetone, and dried at60° C. under vacuum to afford 550 mg (44%) of the title compound as awhite powder. This material was identical by TLC and ¹ H NMR to theproduct of Step I of Example 1.

EXAMPLE 2 1-(2',3'-Bis(hydroxymethyl)cyclobutyl)uracil Step A:N-((2,3-Bis((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutyl)urea

To a stirred solution of 950 mg (2.64 mmol) of the product from Step Dof Example 1 in 50 mL of dry THF was added 0.84 mL (5.34 mmol) oftrimethylsilyl isocyanate (85%, remainder hexamethyldisiloxane) and 0.74mL (5.30 mmol) of triethylamine. After 16 h at reflux, 0.42 mL (2.67mmol) of trimethylsilylisocyanate and 0.37 ml (2.65 mmol) oftriethylamine were added. After a total of 40 h at reflux, 0.84 mL (5.34mmol) of trimethyl isocyanate and 0.74 (5.30 mmol) of triethylamine wereadded. After a total of 80 h at reflux, the cooled reaction mixture wasconcentrated under reduced pressure. Chromatography of the residue on 50g of silica gel with a 95:5 to 85:15/CH₂ Cl₂ :MeOH gradient afforded 825mg (78%) of the title compound as an oil judged by NMR to be 90% pure:Rf 0.17 (silica gel, 60:30:1/hexane:acetone:triethylamine); ¹ H NMR(CDCl₃) 0.04, 0.06 (2 s, 12 H, 2 (CH₃)₂ Si)), 0.90 (s, 18 H, 2(CH₃).sub. 3 C), 1.54 (ddd, 1 H, J=11 Hz, J'=J"=9 Hz, H 4), 1.80-1.92,2.09-2.18 (2 m, 2 H, H-2, H-3), 2.35 (ddd, 1 H, J =11 Hz, J=J'=9 Hz),3.52 (dd, 1 H, J=10 Hz, J'=6 Hz, CH HO), 3.54-3.67 (m, 3 H, H-1, 2 CHHO), 3.75 (dd, 1 H, J=11 Hz, J'=5 Hz), 4.56 (bd, 1 H, J=6 Hz, NH), 4.90(bs, 2 H, NH2); DCI-NH₃ MS, m/z 403 (M+1)⁺.

Step B: 1-(2,'3'-Bis(hydroxymethyl)cyclobutyl)uracil

To a stirred solution of 401 mg (0.996 mmol) of the product from Step Aof Example 2 in 15 mL of pyridine was added 200 uL (1.50 mmol) of (E)-3-ethoxyacryloyl chloride. After 5 h at room temperature, the reactionmixture was concentrated under reduced pressure. Chromatography of theresidue on 50 g of silica gel with a 5:0 to 5:1/hexane:acetone gradientafforded 273 mg (54%) ofN-(N'-(2',3'-Bis((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutyl)carbamoyl)-3-ethoxypropenamideas a colorless oil, judged to be 85% pure by TLC: Rf 0.53(60:30:1/hexane:acetone:triethylamine); DCI- NH₃ MS, m/z 501 (M+1)+.Without further purification, 273 mg (0.545 mmol) of this propenamidewas dissolved in 16.3 mL of 2 M H₂ SO₄ and heated to reflux. After 1.5h, the solution was allowed to cool, the pH adjusted to 6 with solidNaHCO₃, the solution saturated with NaCl, and then continuouslyextracted with EtOAc for three days. The organic extract was dried overMgSO₄ and concentrated under reduced pressure. Chromatography of theresidue on 10 g of silica gel with a 9:1 to 8:2/CH₂ Cl₂ :MeOH gradientafforded 67 mg (54%, 24% overall) of the title compound as an amorphoussolid judged by NMR to be greater than 95% pure: Rf 0.35 (silica gel,80:20/CH₂ Cl₂ :MeOH); ¹ H NMR (CDCl₃, TSP=0.00 ppm) 1.97 (ddd, 1 H,J=J'=J"=11 Hz, H-4'), 2.08-2.20 (m, 1 H, H-3'), 2.47 (ddd, 1 H, J=11 Hz,J'=J"=8 Hz, H-4'), 2.59 (dddd, 1 H, J=J'=9 Hz, J"=J'"=6 Hz, H-2'),3.62-3.74 (m, 4 H, 2 CH₂ O), 4.57 (ddd, 1 H, J=J'=J"=9 Hz, H-1'), 5.87(d, 1 H, J=8 Hz, H-5), 7.84 (d, 1H, J=8 Hz, H 6); FAB MS, m/z 227(M+1)⁺.

EXAMPLE 3 1-(2',3'-Bis(hydroxymethyl)cyclobutyl)cytosine

To 95 mg (0.42 mmol) of the product from Step B of Example 2 was added440 microliters (2.1 mmol) of hexamethyldisilazane and 34 microliters(0.82 mmol) of formamide and the resulting mixture was heated withstirring in a sealed tube at 140° C. After 85 h, 10 mL of MeOH was addedto the cooled reaction mixture, the tube resealed, and heated at 65° C.After 3 h, the cooled reaction mixture was concentrated under reducedpressure, dissolved in 10 mL of water, treated with 50 mg of Darco G-60charcoal, filtered, and concentrated under reduced pressure.Chromatography of the residue on 15 g of silica gel with a 10:0 to7:3/CH₂ Cl₂ :MeOH gradient afforded 68 mg (72%) of the title compound asan amorphous solid, judged by NMR to be 95% pure: Rf 0.27 (silica gel,7:3/CH₂ Cl₂ :MeOH); ¹ H NMR (D₂ O, TSP=0.00 ppm) 1.90 (ddd, 1 H,J=J'=J"=10 Hz, H-4'), 2.06-2.19 (m, 1 H, H- 3'), 2.44-2.58 (m, 2 H,H-2', H-4'), 3.64-3.71 (m, 4 H, 2 CH₂ O), 4.52 (ddd, 1 H, J=10 Hz,J=J'=9 Hz, H-1'), 6.03 (d, 1 H, J=7.5 Hz, H-5), 7.79 (d, 1 H, J=7.5 Hz,H-6); FAB MS, m/z 226 (M+1)⁺, 248 (M+Na)⁺.

EXAMPLE 4 9-(2',3'-Bis(hydroxymethyl)cyclobutyl)adenine Step A:3-((5'-Amino-6'-chloro-4'-pyrimidinyl)amino)-1,2-bis(hydroxymethyl)cyclobutane

A solution of 382 mg (2.28 mmol) of the pruduct from Step E of Example1, 558 mg (3.4 mmol) of 5-amino-4,6-dichloropyrimidine, and 1.59 mL(11.4 mmol) of triethylamine in 25 mL of n-butanol was heated to reflux.After 20 h, 0.30 mL (2.15 mmol) of triethylamine was added, and after 5h more at reflux, the cooled reaction mixture was concentrated underreduced pressure, passed through a column containing 12 mL of Dowex SBR(OH--) resin in 8:2/MeOH:H₂ O, and then concentrated under reducedpressure. Chromatography of the residue on 50 g of silica gel with a100:0 to 85:15/CH₂ Cl₂ :MeOH gradient afforded 384 mg (65%) of the titlecompound, judged to be 95% pure by NMR: Rf 0.33 (silica gel, 85:15/CH₂Cl₂ :MeOH); ¹ H NMR (CD₃ OD) 1.76 (ddd, 1 H, J=11 Hz, J'=J"=9 Hz, H-4),1.95-2.08 (m, 1 H, H-1), 2.16-2.26 (m, 1 H, H-2), 2.46 (ddd, 1 H, J =11Hz, J'=J"=9 Hz, H-4), 3.55, 3.61 (2 dd, 2 H, J=11 Hz, J'=6 Hz, CH₂ O),3.63, 3.70 (2 dd, 2 H, J= 11 Hz, J'=7 Hz, CH₂ O), 4.12 (ddd, 1 H,J=J'=J"=9 Hz, H 1), 7.76 (s, 1 H, H-2'); DCI-NH₃ MS, m/z 259, 261(M+H)⁺.

Step B: 3-(6'-chloro-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane

A solution of 352 mg (1.36 mmol ) of the product from Step A of Example4 in 25 mL of diethoxymethyl acetate was heated to reflux. After 16 h,the cooled solution was concentrated under reduced pressure. To asolution of the residue in 27 mL of toluene was added 13.6 mg ofp-toluenesulfonic acid. After 1 h at room temperature, the reactionmixture was concentrated under reduced pressure and then dissolved in 30mL of MeOH which had been saturated at room temperature with NH₃. After1 h at room temperature, the reaction mixture was concentrated underreduced pressure and coevaporated with 3×5 mL of MeOH. To a solution ofthe residue in 25 mL of MeOH was added p-toluenesulfonic acid until thepH appeared to be 3 by spotting the reaction mixture on moist pH paper.After 1.5 h at room temperature, the reaction mixture was neutralizedwith NH₃ saturated MeOH and then concentrated under reduced pressure.Chromatography of the residue on 25 g of silica gel with a 95:5 to85:15/CH₂ Cl₂ :MeOH gradient afforded 254 mg (70%) of the titlecompound, judged to be 93% pure by NMR: Rf 0.34 (silica gel, 85:15/CH₂Cl₂ :MeOH); ¹ H NMR (CD₃ OD) 2.20-2.33 (m, 1 H, H-1), 2.49 (ddd, 1 H,J=11 Hz, J'=J"=9 Hz, H-4), 2.64 (ddd, 1 H, J=11 Hz, J'=J"=9 Hz, H-4),3.01 (dddd, 1 H, J =J'=9 Hz, J"=J'"=6 Hz, H-2), 366-3.78 (m, 4 H, 2 CH₂O), 4.88 (ddd, 1 H, J=J'=J"=9 Hz, H-1), 8.68, 8.73 (2 s, 2 H, H-2 andH-8); DCI NH₃ MS, m/z 269, 271 (M+H)⁺.

Step C: 9-(2,'3'-Bis(hydroxymethyl)cyclobutyl)adenine

A solution of 102.5 mg (0.38 mmol) of the product from Step B of Example4 in 3 mL of MeOH and 5 mL of liquid NH₃ was heated at 60° C. in asealed tube. After 48 h, the reaction mixture was cooled to -78° C. andthe tube was opened. After the NH₃ had evaporated, the reaction mixturewas concetrated under reduced pressure. Crystallization of the residuefrom 0.7 mL of MeOH afforded 75 mg (79%) of the title compound with m.p.179°-182° C. Recrystallization of a portion of this material raised them.p. to 181°-183° C.: Rf 0.19 (silica gel, 8:2/CH₂ Cl₂ :MeOH); ¹ H NMR(D₂ O, TSP=0.00 ppm) 2.21 (ddd, 1 H, J=J'=10 Hz, J"=9 Hz, H-4'),2.21-2.36 (m, 1 H, H-3 '), 2.70 (ddd, 1 H, J=10 Hz, J'=J"=8 Hz, H-4'),2.80 (dddd. 1 H, J=J'=9 Hz, J"=J'"=5 Hz, H-2'), 3.75, 3.77 (2 d, 4 H,J=5 Hz, 2 CH₂ O), 4.66 (ddd, 1 H, J=J'=9 Hz, J"=8 Hz, H-1'), 8.14, 8.27(2 s, 2 H, H-2 and H-8); DCI NH₃ MS, m/z 250 (M+H)⁺ ; FAB MS, m/z 250(M+H)⁺ ; exact mass calcd for C₁₁ H₁₆ N₅ O₂ (M+H)⁺ 250.1304, found250.1303.

EXAMPLE 5 9-((3'-Hydroxymethyl)cyclobutyl)guanine Step A:N-(Benzyloxycarbonyl-3-methylenecyclobutanamine

To a stirred solution of 26.7 g (238 mmol) of 3-methylenecyclobutanecarboxylic acid (Cripps, H. N.; Williams, J. K.; Sharkey, W. H. J. Am.Chem. Soc. 1959, 81, 2723-2728) in 100 mL of toluene at 0° C. was added36.4 mL (262 mmol) of triethylamine and then 72.1 g (262 mmol) ofdiphenylphosphoryl azide. The reaction mixture was then heated at 80°C., and after 1 h, 28.33 g (262 mmol) of benzyl alcohol was added. After15 h at 85° C., the cooled reaction mixture was poured into 1 L ofether, washed with saturated aqueous NaHCO₃, and then saturated aqueousNaCl, dried over MgSO₄, and then concentrated under reduced pressure.Chromatography of the residue in three portions on 1400 g of silica gelwith 80:20/hexane:EtOAc afforded 35.4 g (63%) of the desired compound.

MS DCI/NH₃ M?Z: 218 (M+H)⁺, 235 (M+NH₄)⁺ ; ¹ H NMR (CDCl₃) 2.60 (m, 2H),3.05 (m, 2H), 4.20 (m, 1H), 4.83 (m, 2H), 5.21 (s, 2H), 7.45 (m, 5H).

Step B: 3-((N-benzyloxycarbonyl)amino)cyclobutanemethanol

To a stirred solution of 17.47 g (80.5 mmol) of the product from Step Aof Example 5 in 25 mL of THF was added 145 mL (145 mmol) of 1M BH₃ inTHF. After 2 h at room temperature, 80 mL of 6N aqueous NaOH was added.After the vigorous release of H₂ had subsided, 22 mL of 30% H₂ O₂ wasthen added. After 45 min, solid K₂ CO₃ was added. After the reactionmixture had stirred for an additional 30 min, the reaction mixture wasfiltered through celite, diluted with 500 mL of EtOAc, washed withsaturated aqueous NaCl, dried over Na₂ SO₄, and then concentrated underreduced pressure. Chromatography of the residue on 1200 g of silica gelwith a 1:1 to 9:1 ethyl acetate/hexane gradient afforded 12.01 g (63.5%)of the desired compound.

Step C: 3-Amino-cyclobutanemethanol

A stirred solution of 12.01 g (51.1 mmol) of the product from Step B ofExample 5 in 200 mL of MeOH was hydrogenated over 1.2 g of 20% Pd/C,filtered, and then concentrated under reduced pressure to afford 4.98 g(96%) of the desired compound.

Step D: 3-((2'-Amino6'-chloro-4'-pyrimidinyl)amino)cyclobutanemethanol

A solution of 4.98 g (49.3 mmol) of the product from Step C of Example5, 16.17 g (98.6 mmol) of 2-amino-4,6-dichloropyrimidine, and 6.36 mL(49.3 mmol) of triethylamine in 40 mL of 2-methoxyethanol was heated toreflux. After 2 h, the reaction mixture was allowed to cool, dilutedwith 100 mL of dichloromethane, and filtered. The filtrate was thenconcentrated under reduced pressure, triturated with 100 mL of 10%isopropanol in EtOAc, filtered, and then concentrated under reducedpressure. Chromatography of the residue on 500 g of silica gel with a95:5 to 90:10/EtOAc: isopropanol gradient afforded 7.10 g (63%) of thedesired compound: Rf 0.50 (silica gel, 90:10/EtOAc:isopropanol); DCI NH₃MS, m/z 229, 231 (M+H)⁺.

Step E:3-((6'-Chloro-2,'5'-diamino-4'-pyrimidinyl)amino)-cyclobutanemethanol

Following the procedure of Step G of Example 1, but substituting 4.762 g(37.3 mmol) of the product from Step D of Example 5 for the product fromStep F of Example 1, afforded, after purification of the crude productby chromatography on 500 g of silica gel with 90:10/EtOAc: isopropanol,1.22 g (27%) of the desired compound: Rf 0.43 (silica gel, 9:1/EtOAc:isopropanol); DCI NH₃ MS, m/z 244, 246 (M+H)⁺.

Step F: 3-(2'-Amino-6'-chloro-9'H-purin-9'-yl)cyclobutanemethanol

To a stirred solution of 1.22 g (5.37 mmol) of the product from Step Eof Example 5 in 10 mL of DMF at 0° C. was added a solution of 0.50 mL ofconcentrated aqeuous HCl in 10 mL of triethyl orthoformate. The solutionwas allowed to gradually warm to room temperature. After 15 h, thereaction mixture was concentrated under reduced pressure and thencoevaporated with 3×10 mL of water. The residue was dissolved in 50 mLof 50% aqueous HOAc. After 5 h, the reaction mixture was concentratedunder reduced pressure. The residue was dissolved in 50 mL of 10% NH₃ inMeOH. After 4 h, the reaction mixture was concentrated under reducedpressure. Chromatrography of the residue on 150 g of silica gel with85:15/CH₂ Cl₂ :MeOH afforded 1.018 g (75%) of the desired compound: Rf0.26 (silica gel, 90:10/CH₂ Cl₂ :MeOH); DCI NH₃ MS, m/z 254, 256 (M+H)⁺.

Step G: 9-(3'-(Hydroxymethyl)cyclobutyl)guanine

A solution of 1.018 g (4.02 mmol) of the product from Step F of Example5 in 30 mL of 1N HCl was heated to reflux for 5 h and then concentratedunder reduced pressure. The residue was dissolved in a small amount ofwater and the pH was adjusted to 7 with 1N NaOH. The resultingprecipitate was removed by filtration, redissolved in MeOH, filtered,and then concentrated under reduced pressure and dried in vacuo toafford 666 mg (70%) of the desired compound as a white powder: Rf 0.21(silica gel, 80:20:1/CH₂ Cl₂ MeOH:NH₃); DCI NH₃ MS, m/z 236 (M+H)⁺.

EXAMPLE 63-(2',6'-Diamino-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane

To a solution of 100 mg (0.272 mmol) of the product of Example 22 in 5ml of EtOH was aded 10 ml of liquid ammonia and the resulting mixturewas heated at 100° C. in a steel bomb. After 15 hours, the reactionmixture was allowed to cool, the ammonia allowed to evaporate and theremaining solution was concentrated under reduced presure.Chromatography of the residue on 10 g of C-18 bonded silica gel with a100:0 to 60:40/water:methanol gradient afforded 45.6 mg (64%) of thetitle compound as a white solid. ¹ H NMR (D₂ O, TSP=0.00 ppm) 2.16 (ddd,1H, J=J'=J"=9Hz, H-4), 2.14-2.30 (m, 1H), 2.60-2.75 (m, 2 H),3.68-3.80)m, 4 H, 2 CH₂ O), 4.48 (ddd, 1 H, J=J'=J"=9 Hz, H-3), 7.98 (s,1 H, H-8'); FAB MS, m/z 265 (M+H).

EXAMPLE 7 3-(2'-Amino-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane

To a solution of the product of Example 24 in 50 mL of MeOH was added 5mL of concentrated NH₄ OH. After 24 hours, the solution was concentratedunder reduced pressure. Chromatography of the residue on silica gel with95:5 to 60:40 gradient of CHCl₃ /MeOH afforded 480 mg of the tiltlecompound. Analysis calculated for C₁₁ H₁₅ N₅ O₂ 0.1 H₂ O: C, 52.62; H,6.10: N, 27.89. Found: C, 52.80; H, 6.14; N, 27.73. DCI/NH₃ MS, m/z 250(M+H)⁺.

EXAMPLE 8 3-(6'-Chloro-9'H-purin-9'-yl)cyclobutylmethanol Step A:3-((N-t-butyloxycarbonyl)amino)methylenecyclobutane

In a round bottom flask were placed 5.0 g of 3-methylenecyclobutanecarboxylic acid (see Step A of Example 5) and 75 mL of t-butylalcohol.To the system were added 10.6 mL of diphenylphosphoryl azide and 6.8 mLof triethylamine. The reaction mixture was heated at reflux for 14 h,concentrated, and diluted with ether. This solution was washed withaqueous phosphoric acid, aqueous sodium bicarbonate, and brine, and thendried over sodium sulfate. The crude material was purified bychromatography to afford 4.0 g of the desired compound.

Step B: 3-((N-t-butyloxycarbonyl)amino)cyclobutanemethanol

In a round bottm flask were placed 3.85 g of the product from Step A ofExample 8 and 10 mL of THF. To the system, at 0° C., was added 42 mL of1M BH3 in THF. The reaction mixture was stirred at 0° C. for 30 min androom temperature for 3 h. Then 10 mL of 1M BH3 in THF was added to thesystem, and the mixture was stirred at room temperature for 1 h. Thesystem was cooled to 0° C., and 26 mL of 6M aqueous NaOH was cautiouslyadded to the system followed by 7.7 mL of 30% H₂ O₂. The mixture wasstirred at room temperature overnight. To the system was added solid K₂CO₃ followed by ethyl acetate and water. The layers were separated, andthe organic layer was washed with aqueous phosphoric acid, aqueoussodium bicarbonate, and brine, and then dried and concentrated. Thecrude material was purified by column chromatography to afford 2.1 g ofthe desired compound.

Step C: 3-(Hydroxymethyl)cyclobutylamine hydrochloride

In a round bottom flask were placed 0.94 g of the product from Step B ofExample 8 and 19 mL of 4M HCl in 1:2 H₂ O/THF, and this solution wasstirred at room temperature for 1 h and then concentrated to afford thedesired compound.

Step D: 3-((5'-Amino-6'-chloro-4'-pyrimidinyl)amino)cyclobutanemethanol

In a round bottom flask were placed the crude material from Step C ofExample 8, 10.8 mL of n-butanol, 2.7 mL of triethylamine, and 1.55 g of5-amino-4,6-dichloropyrimidine. The mixture was heated at 120° C. for 10h, concentrated, and purified by column chromatography to afford 923 mgof the desired compound: m.p. 152°-156° C.

Step E: 3-(6'-chloro-9'H-purin-9'-yl)cyclobutanemethanol

In a round bottom flask were placed 0.86 g of the product from Step D ofExample 8, 10 mL of triethylorthoformate, 5 mL of N-methylpyrrolidinone,and 0.5 mL of concentrated HCl. The reaction mixture was stirred at roomtemperature for 1.5 h, 0.2 mL more HCl and 2 mL more oftriethylorthoformate were added, and after a total of 3 h, the reactionmixture was concentrated. Flash chromatography afforded 0.33 g of thedesired compound as a light yellow oil. Also isolated was 200 mg of6-chloro-9-(3'-formyloxymethylcyclobutyl)purine.

EXAMPLE 93-(6'-Chloro-9'H-purin-9'-yl)-N-butyloxycarbonylaminomethylcyclobutaneStep A: N-t-butyloxycarbonyl-1-aminomethyl-3-methylenecyclobutane

In a round bottom flask were placed 10 g of1-aminomethyl-3-methylenecyclobutane (Caserio, F. F.; Parker, S. H.;Piccolini, R.; Roberts, J. D. J. Am. Chem. Soc. 1958, 80, 5507-5513) and80 mL of dichloromethane. To this solution, at 0° C., were added 43.4 mLof triethylamine followed by 24.5 g of di-t-butyl dicarbonate over aperiod of 20 min. The reaction mixture was stirred for 3 days, washedwith aqueous phosphoric acid, saturated aqueous sodium bicarbonate andbrine, dried, and then concentrated to afford 19.7 g of the titlecompound.

Step B: N-t-Butoxycarbonyl-3-aminomethylcyclobutanone

In a round bottom flask were placed 9 g of the product from Step A ofExample 9, 100 mL of methanol, and 400 mL of dichloromethane. Thesolution was cooled to -78° C., and ozone was bubbled through thereaction mixture until the solution was blue. The system was flushedwith nitrogen for 2.5 h, and then treated with 34 mL of dimethylsulide.After 1 h at -78° C., 0° C. for 1 h, and room temperature for 1 h, thesolution was stored in a refrigerator at 5° C. overnight before beingconcentrated. The crude material was purified by column chromatographyto afford the title compound.

Step C: N-t-butyloxycarbonyl-3-aminomethylcyclobutanamine

In a round bottom flask were placed 4 g of the product from Step B ofExample 9 and 12 mL of methanol. In a separate flask were placed 1.46 gof hydroxylamine hydrochloride, 18 mL of water, and 1.76 g of sodiumbicarbonate. The resulting solution was added to the intitial flask, andthe resulting mixture was stirred at room temperature for 3 h. Thereaction mixture was then diluted with ethyl acetate, washed withsaturated aqueous sodium bicarbonate, and dried. The solution wasconcentrated to afford 4.0 g of the oxime as a white solid, m.p. 94°-98°C. This oxime was dissolved in 250 mL of methanol. To the system wasadded 4 g of Raney nickel, and the mixture was placed under 4 atm ofhydrogen for 4 h. The catalyst was removed by filtration through celite.Concentration afforded 3.53 g of the title compound.

Step D:3-((5'-Amino-6'-chloro-4'-pyrimidinyl)amino)-N-butyloxycarbonyl-aminomethylcyclobutane

The procedure of Step D of Example 8 was repeated, replacing the productof Step C of Example 8 with the product of Step C of Example 9 to obtainthe title compound as a foamy yellow solid. The diasteromeric mixturewas separated by column chromatography: cis isomer, m.p. 149°-152° C.;trans isomer, 89°-94° C.

Step E:3-(6'-Chloro-9'H-purin-9'-yl)-N-butyloxycarbonylaminomethylcyclobutane

The procedure of Step E of Example 8 was repeated replacing the productfrom Step D of Example 8 with the product from Step D of Example 9 toobtain the title compound as a white solid, m.p. 106°-110° C.

EXAMPLE 10 1-((3'-Hydroxymethyl)cyclobutyl)thymine

In a round bottom flask were placed 2.68 g of 3-methoxymethacrylic acidchloride and 25 mL of benzene. To the system was added 6.4 g of silvercyanate, and the mixture was heated at reflux for 40 min. In a roundbottom flask were placed 1.0 g of the product from Step C of Example 5,30 mL of DMF, and 10 mL of ether, and the system was cooled to -15° C.To the system was added 12.5 mL of the acylisocyanate prepared above,the solution was stirred at -15° C. for 2 h and allowed to stand in arefrigerator overnight. The reaction mixture was concentrated and thecrude material was purified by column chromatography to afford 1.7 g ofa solid, m.p. 120°-121° C. In a round bottom flask were placed 150 mg ofthis material and 5 mL of 2N aqueous sulfuric acid, and the reactionmixture was heated at reflux for 2 h. The mixture was brought to pH 7with aqueous barium hydroxide, filtered, and the filtrate wasconcentrated. This reaction was repeated using 450 mg of the materialprepared above, and the crude products from each reaction were combinedand subjected to column chromatography to afford 429 mg of the titlecompound, m.p. 162°-164° C.

EXAMPLE 11 1-((3'-Hydroxymethyl)cyclobutyl)uracil

The procedure of Example 10 was repeated, replacing 3-methoxymethacrylicacid chloride with 3-ethoxyacrylic acid chloride to obtain the titlecompound, m.p. 44°-52° C.

EXAMPLE 12 1-((3'-Hydroxymethyl)cyclobutyl)cytosine

The procedure of Example 3 is repeated, replacing the product of Step Bof Example 2 with the product of Example 11 to obtain the desiredcompound.

EXAMPLE 139-(((3'-(1,1-dimethylethyl)dimethylsilyl)oxymethyl)-2'-(hydroxymethyl)cyclobutyl)guanine

To a solution of 1 mmol of the product from Step K of Example 1 in 20 mLof pyridine is added 1.5 equivalents of t-butyldimethylsilyl chloride.After 24 h at room temperature, the reaction mixture is concentratedunder reduced pressure. Chromatography of the residue affords thedesired product.

EXAMPLE 149-(((3'-(1,1-dimethylethyl)dimethylsilyl)oxymethyl)-2'-(methanesulfonyloxymethyl)cyclobutyl)guanine

To a solution of 0.5 mmol of the product obtained from severalexecutions of the procedure of Example 13 in 10 mL of dichloromethane at-60° to 0° C. is added 1.5 equivalents of triethylamine and 1.1equivalents of methanesulfonyl chloride. After 1 h, the reaction mixtureis treated with 1 equivalent of ethanol and then concentrated underreduced pressure. Rapid chromatography affords the desired compound.

EXAMPLE 159-(((3'-(1,1-dimethylethyl)dimethylsilyl)oxymethyl)-2'-(bromomethyl)cyclobutyl)guanine

To a solution of 0.5 mmol of the product obtained from severalexecutions of the procedure of Example 14 in 3 mL of DMF is added 1.1equivalent of tetra-n-butylammonium bromide and the resulting mixture isheated at 50° C. for 24 h. The reaction mixture is then concentratedunder reduced pressure and chromatography of the residue affords thedesired compound.

EXAMPLE 16 9-(3'-hydroxymethyl-2'-bromomethylcyclobutyl)guanine

A solution of 0.5 mmol of the product obtained from several executionsof the procedure of Example 15 in 2 mL of MeOH is treated with 1equivalent of trimethylsilyl chloride. After 1 h at room temperature,the reaction mixture is concentrated under reduced pressure.Chromatography of the residue affords the desired compound.

EXAMPLE 17 9-(3'-Hydroxymethyl-2'-methylcyclobutyl)guanine

A solution of 0.5 mmol of the product obtained from several executionsof the procedure of Example 15 in 5 mL of toluene at reflux is treatedwith 1 equivalent of tri-n-butyltin hydride. After 1 h, the reactionmixture is concentrated, and then deprotected and purified accroding tothe procedure of Example 16 to afford the title compound.

EXAMPLE 18 9-(3'-Hydroxymethyl-2'-azidomethylcyclobutyl)guanine

The procedures of Examples 15 and 16 are repeated, buttetra-n-butylammonium azide is substituted for tetra-n- butylammoniumbromide.

EXAMPLE 19 9-(3'-Hydroxymethyl-2'-aminomethylcyclobutyl)guanine

The product of Example 18 is dissolved in water and hydrogenated over Pdon carbon to afford the desired compound.

EXAMPLE 20 9-(2,'3,'-Bis(acetoxymethyl)cyclobutyl)guanine

To a stirred solution of 207 mg (0.780 mmol) of the product from Step Kof Example 1 in 10 mL of acetonitrile is added 287 uL (2.06 mmol) oftriethylamine, 7 mg (0.0585 mmol) of 4-dimethylaminopyridine, and 177 uL(1.87 mmol) of acetic anhydride. After 3 hours at room temperature, theclear solution is treated with 1 mL of methanol, concentrated underreduced pressure, redissolved in 2 mL of methanol, and then added to 50mL of water. The resulting precipitate was removed by filtration, washedwith water, and then dried under vacuum at 60° C. to afford 226 mg (83%)of the title compound as a white solid. ¹ H NMR (CDCl₃) 2.03, 2.11 (2s,6 H, 2 CH₃), 2.29-2.46 (m, 2 H), 2.54-2.65 (m, 1 H), 2.96-3.05 (m, 1 H),4.18-4.30 (m, 4 H, 2 CH₂ O), 4.52 (ddd, 1 H, J=J'=J"=9 Hz, H-1'), 7.59(s, 1 H, H-8).

EXAMPLE 21 3-(6'-Chloro-9'H-purin-9'-yl)-aminomethylcyclobutanehydrochloride

In a round bottom flask were placed the product of Step E of Example 9(210 mg) and 1.4 mL of 4.5M HCl in dioxane. After 1.5 hours, thereaction mixture was concentrated to afford the title compound as awhite solid. m.p. >250° C. (d).

EXAMPLE 22 9-(2',3'-Bisacetoxymethyl)cyclobutyl)-2-amino-6-chloropurine

To a stirred solution of 208 mg (0.595 mmol) of the product of Example20 in 1.83 mL (19.6 mmol) of POCl₃ was added 93 uL (0.58 mmol) ofN,N-diethylaniline, and the resulting mixture was heated at 70° C. After1 hour, the excess POCl₃ was removed by evaporation at reduced pressure.The residue was then dissolved in 100 mL of dichloromethane and washedwith 5×50 mL of water, dried over MgSO₄, and then concentrated underreduced pressure. Chromatography of the residue on 20 g of silica gelwith 95:5/CH₂ Cl₂ :MeOH afforded 153 mg (70%) of the title compound as alight yellow oil. DCI NH₃ MS, m/z 368, 370 (M+H)⁺.

EXAMPLE 23 9-(2',3'-Bis(hydroxymethyl)cyclobutyl-8-bromoguanine

To a suspension of 265 mg (1.00 mmol) of the product from Step K ofExample 1 in 50 mL of water was added 9.0 mL (1.75 mmol) of a 0.194Msolution of bromine in water in several small portions. After 4 hours,the reaction was cooled in an ice bath. The product was then removed byfiltration, washed with water and acetone, and then dried over P₂ O₅ toafford 232 mg (67%) of the title compound as an off-white solid. ¹ H NMR(D₂ O, TSP=0.00 ppm) 2.12 (m, 1 H), 2.47 (ddd, 1 H, J=11 Hz, J'=J"=9 Hz,H-4), 2.75 (ddd, 1 H, J=11 Hz, J'=J"=10 Hz, H-4), 3.34-3.43 (m, 1H),3.70 (d, 1 H, J=6 Hz, CH₂ O), 3.80 (d, 1 H, J=6 Hz, CH₂ O), 4.74 (ddd, 1H, J=10 Hz, J'=J"=9 Hz, H-1). FAB MS, m/z 344,346 (M+H)⁺.

EXAMPLE 24 9-(2',3'-Bis(acetoxymethyl)cyclobutyl)-2-aminopurine

A mixture of 2.63 g (7.15 mmol) of the product from Example 22, 1.18 g(14.3 mmol) of anhydrous sodium acetate, 1.0 g of 10% Pd on carbon and100 mL of methanol was stirred under 1 atmosphere of hydrogen. After 12hours, the reaction mixture was filtered and concentrated to a residueunder reduced pressure. To the residue was added water and ethylacetate, and the phases were separated. The aqueous phase was extractedwith several portions of ethyl acetate and the combined organic extractswere concentrated under reduced pressure. Chromatography of the residueon silica gel with a 100:0 to 90:10/ethyl acetate:methanol gradientafforded 1.60 g (67%) of the title compound as an oil. DCI NH₃ MS, m/z334 (M+H)⁺.

EXAMPLE 25 [1'R,2'R,3'R]-9-(2',3')-Bis(hydroxymethyl)cyclobutyl)guanineStep A: [1R,2R]-1,2-Bis(methoxycarbonyl)-3-methylenecyclopropane

1. The quinine salt (W. von E. Doering and D. Roth, Tetrahedron, 26,2825-2835 (1970)) of

3-methylenecyclopropane-trans-1,2-dicarboxylic acid (F. Feist, ChemischeBerichte, 26, 750 (1893)) (28.383 g, 60.9 mmol) was dissolved in 1 L of10% aqueous sulfuric acid solution. The resultant solution was extractedthoroughly with diethyl ether as follows: the aqueous solution wasextracted three times with 3 portions of diethyl ether. Each group ofthree extracts was pooled, washed with pH 2 brine, dried over anhydrousmagnesium sulfate and the solvent evaporated to give 6.871 g of[1R,2R]-3-methylenecyclobutane-trans-1,2-dicarboxylic acid (m.p.=210°C.) from the first extracts, 0.924 g of[1R,2R]-3-methylenecyclopropane-trans-1,2-dicarboxylic acid (m.p.=210°C.) from the second extracts and 0.493 g of[1R,2R]-3-methylenecyclopropane-trans-1,2-dicarboxylic acid (m.p.=210°C.) from the third extracts, for a total of 8.29 g of diacid; [α]_(D) ²³+151.6° (c 0.76; EtOH), [α]₅₄₆ ²³ +179.3° (c 0.76; EtOH); lit. * [α]₅₄₆²³ +176° (c 0.7; EtOH).

2. Diazomethane was generated from 50 g of N-methyl-N-nitroso-p-toluenesulfonamide (Diazald®, commercially available from Aldrich Chemical Co.)in diethyl ether. The ether solution of diazomethane was added to anether solution of [1R,2R]-3-methylenecyclopropane-trans-1,2-dicarboxylicacid (8.288 g, 55.4 mmol), from Step A1, until a yellow color developedand persisted. After 10 minutes the excess diazomethane was quenchedwith glacial acetic acid and the ether solution was washed with diluteaqueous sodium bicarbonate solution and brine, dried over anhydrousmagnesium sulfate, filtered and concentrated to give 8.812 g (88.8%yield from the diacid) of the title compound; [α]_(D) ²³ =+122.9° (c1.06; CCl₄), [α]₅₄₆ ²³ =+144.9° (c 1.06; CCl₄); lit. (W. von E. Doeringand D. Roth, Tetrahedron, 26, 2825-2835 (1970) [α]₅₄₆ ²³ +145° (c 0.7;CCl₄).

Step B: [1R,2R]-1,2-Bis(hydroxymethyl)-3-methylenecyclopropane

A solution of 8.748 g (51.5 mmol) of[1R,2R]-bis(methoxycarbonyl)-3-methylenecyclopropane from Step A2 in 25mL of toluene was added to 206 mL of 1.5M diisobutyl aluminum hydride(309 mmol) in toluene which had been cooled to -70° C. in a dryice-acetone bath. The reaction mixture was stirred at -70° C. overnightand then quenched with 22.2 mL of methanol followed by 37.1 mL of water.The aluminum salts were filtered and washed with ethyl acetate andmethanol. The ethyl acetate washes were combined and the solution wasdried over anhydrous magnesium sulfate, filtered and concentrated togive 6.53 g of the title compound. The washed salts were suspended inmethanol and the suspension was filtered. The filtrate was concentratedto give an additional 1.166 g of the title compound for a total of 7.696g (131% yield) of crude product which was taken on to the next stepwithout purification; MS DCI-NH₃ M/Z: 132 (M+NH₄)⁺.

Step C:[1R,2R]-1,2-Bis(((1',1'-dimethylethyl)dimethylsilyl)oxymethyl)-3-methylenecyclopropane

The product of Step B (5.633 g, 49.4 mmol) was dissolved in 75 mL ofN,N-dimethylformamide (DMF) and 16.8 g (247. mmol) of imidazole wasadded. The reaction mixture was cooled in an ice bath and 22.33 g (148mmol) of t-butyldimethylsilyl chloride was added in one portion. Thereaction mixture was allowed to warm to ambient temperature by removingthe ice bath and stirring the reaction mixture overnight. The reactionwas quenched with 10 mL of methanol, stirred for 0.5 h and concentratedin vacuo. The residue was diluted with 200 mL of ethyl acetate and theethyl acetate solution was washed with aqueous sodium bicarbonatesolution and brine, dried over anhydrous magnesium sulfate, filtered andconcentrated in vacuo. The residue was purified on a 5×30 cm silica gelcolumn eluted with methylene chloride to give 12.084 g (71.5% yield) ofthe title compound; MS DCI-NH₃ M/Z: 360 (M+NH₄)⁺.

Step D:[4R,5R]-4,5-Bis(((1',1'-dimethylethyl)dimethylsilyl)oxymethyl)-1-oxaspiro[2,2]pentane

A solution of 15.8 g (46.2 mmol) of[1R,2R]-1,2-bis(((1,1-dimethylethyl)-dimethylsilyl)oxymethyl)-3-methylenecyclopropane,from Step C, in 200 mL of methylene chloride was cooled in an ice bathand treated with 15.945 g (46.2 mmol) of 50% meta-chloroperoxybenzoicacid (mCPBA). The reaction mixture was allowed to warm to ambienttemperature and stirred overnight. TLC analysis on silica gel plateseluted with 10% hexane in ethyl acetate showed unreacted startingmaterial, so 8.0 g of mCPBA was added. After stirring at ambienttemperature for 6 h, another 2.16 g of mCPBA was added and stirringcontinued for 1.25 h. The reaction mixture was then diluted withmethylene chloride, washed with 5% aqueous sodium bisulfite solution, 5%aqueous sodium bicarbonate solution and brine and then dried overanhydrous magnesium sulfate, filtered and concentrated to give 12.752 g(77% yield) of the title compound; MS DCI-NH₃ M/Z: 376 (M+NH₄)⁺.

Step E: [2R,3R]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-cyclobutanone

A solution of 12.752 g (35.6 mmol) of[4R,5R]-4,5-bis(((1,1-dimethylethyl)-dimethylsilyl)oxymethyl)-1-oxaspiro[2,2]pentane,from Step D, in 50 mL of methylene chloride was added to a solution of3.814 g (28.5 mmol) of lithium iodide in 200 mL of methylene chloridewhich had been cooled in an ice bath. After stirring the reactionmixture for 1 h at 0° C., the ice bath was removed and the reactionmixture was stirred for 20 minutes at ambient temperature. The reactionmixture was then washed with 5% aqueous sodium bicarbonate solution, 5%sodium bisulfite solution and brine, dried over anhydrous magnesiumsulfate, filtered and concentrated under reduced pressure to give 12.317g (96.6% crude yield) of the title compound which was taken on to thenext step without purifiaction; MS DCI-NH₃ M/Z: 376 (M+NH₄)⁺.

Step F:[2R,3R]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-cyclobutanoneO-methyl oxime

A solution of 12.317 g (34.9 mmol) of[2R,3R]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanone,from Step E, in 20 mL of pyridine was added to a solution of 3.160 g(37.8 mmol) of methoxylamine hydrochloride in 80 mL of pyridine. Afterstirring the reaction mixture for 70 min at ambient temperature, it wasconcentrated to approximately 1/4 of the original volume then dilutedwith ethyl acetate, washed with saturated aqueous sodium bicarbonatesolution, dried over anhydrous magnesium sulfate, filtered andconcentrated in vacuo. The residue was purified by flash chromatographyon a 5×38 cm silica gel column eluted with 1 L of hexane and 5% acetonein hexane to give 10.228 g (75.7% yield) of the title compound as amixture of geometrical isomers. .MS DCI-NH₃ M/Z: 388 (M+H)⁺.

Step G:[1R,2R,3R]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-cyclobutylamine

To 4.74 g (125 mmol) of sodium borohydride in 125 mL of tetrahydrofuran(THF) was added (slowly) 14.25 g (9.63 mL, 125 mmol) of trifluoroaceticacid (TFA), followed by 10.228 g (26.4 mmol) of[2R,3R]-2,3-Bis(((1,1-dimethylethyl)di-methylsilyl)oxymethyl)cyclobutanone-O-methyloxime, from Step F, in 25 mL of THF. After stirring the reaction mixtureat ambient temperature for 1.5 h, it was concentrated, diluted withmethylene chloride and washed with brine. An emulsion developed whichcleared up after filtration. The methylene chloride solution was driedovernight over anhydrous magnesium sulfate, filtered and concentrated togive 10.98 g of crude title compound which was taken on to the next stepwithout purification; MS DCI-NH₃ M/Z: 360 (M+NH₄)⁺.

Step H: [1R,2R,3R]-3-((2'-Amino-3',4'-dihydro-4'-nitro-4'-oxo-6'-pyrimidinyl)-amino-1,2-bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutane

The crude product from Step G was combined with 5.032 g (20.4 mmol) of2-amino-6-chloro-3,4-dihydroxy-5-nitro-4-oxopyrimidine (prepared asdescribed by C. Temple et al. in J. Org Chem, 40, 3141-3142 (1975)) and5.5 mL (39.6 mmol) of triethylamine in 40 mL of DMF and this mixture washeated at 50° C. for 3.5 h. The solvent was evaporated in vacuo and theresidue was triturated with diethyl ether and filtered. The filtrate waswashed with water and brine, dried over anhydrous magnesium sulfate,filtered and concentrated. The residue was purified on a 3×55 cm silicagel column eluted with 5% methanol in methylene chloride to give 10.8 g(79.7% yield from the O-methyl oxime) of the title compound; MS DCI-NH₃M/Z: 514 (M+H)⁺.

Step I: 9-([1'R,2'R,3'R]-2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

[1R,2R,3R]-3-((2'-Amino-3'-dihydro-5'-nitro-4'-oxo-6'-pyrimidinyl)-amino-1,2-bis(((1,1-dimethyl)dimethylsilyl)oxymethyl)cyclobutane(2.0 g, 3.9 mmol) from Step H was hydrogenated at 4 atmospheres ofhydrogen, in 150 mL of formic acid, over 0.4 g of 10% palladium oncarbon for 1.25 h. The catalyst was removed by filtration and thefiltrate was heated at 130° C. for 8 h. The solvent was then evaporatedin vacuo and the residue slurried in water. The water was removed invacuo and water was added to the residue to form a slurry which wasevaporated in vacuo. The residue was again slurried in water and theslurry was filtered. The precipitate was washed with water and treatedwith 100 mL of concentrated ammonium hydroxide solution at ambienttemperature for approximately 1 h. The ammonium hydroxide solution wasthen filtered and the filtrate concentrated. The solid residue wascrystallized from water to give 523 mg (50% yield) of the title compoundas off-white needles, [α]_(D) ²³ =+22.4° (c 0.32; 0.01N NaOH); MSDCI-NH₃, M/Z: 266 (M+H)⁺ ; ¹ H NMR (D₂ O) δ 2.17 (ddd, 1H, J+J'=10 Hz,J"32 9 Hz, H-4'), 2.16-2.28, 2.58-2.66, 2.69-2.78 (3m, 3H, H-4', H-2',H-3'), 3.72, 3.74 (2d, 4H, J=6 Hz, 2 CH₂ O), 4.51 (ddd, 1H, J=J'=J"=9Hz, H-1'), 7.97 (s, 1H, H-8).

HPLC analysis of the title compound on a Nucleosil Chiral-1 column(Nucleosil is a registered trademark of Macherey Nagel. The NucleosilChiral-1 column is available commercially from Alltech Associates, Inc.)using a mobile phase consisting of 0.5 millimolar aqueous copper acetateadjusted to pH 5.75 with glacial acetic acid indicated an enantiomericpurity exceeding the limit of detection. The enantioselectivity factorof this system was 1.22.

EXAMPLE 26 [1'R,2'R,3'R]-9-(2',3'-Bis(hydroxymethyl)cyclobutyl)adenine

Following the procedures described in Example 4, replacing the productof Step E of Example 1 with the product of Step G of Example 25, thetitle compound is prepared with both hydroxyl groups protected witht-butyldimethylsilyl groups. The protecting groups are removed asdescribed in Step E of Example 1.

EXAMPLE 27 [1'R,2'R,3'R]-1-(2',3'-Bis(hydroxymethyl)cyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with the product of Step G of Example 25, thetitle compound is prepared.

EXAMPLE 28 [1'R,2'R,3'R]-1-(2',3'-Bis(hydroxymethyl)cyclobutyl)thymine

Following the procedures described in Example 2, replacing, in Step A,the product of Step D of Example 1 with the product of Step G of Example25, and replacing, in Step B, (E)-3-ethoxyacryloyl chloride with3-methoxymethacryloyl chloride, the title compound is prepared.

EXAMPLE 29 [1'R,2'R,3'R]-1-(2',3'Bis(hydroxymethyl)cyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 27, the titlecompound is prepared.

EXAMPLE 30 [1'S,2'S,3'S]-9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

Following the procedures described in Example 25, replacing the[1R,2R]-3-methylenecyclopropane-trans-1,2-dicarboxylic acid in Step Hwith [1R,2R]-3-methylenecyclopropane-trans-1,2-dicarboxylic acid, thedesired compound is prepared. The [1S,2S]-diacid is obtained from theresolution of 3-methylenecyclopropane-trans-1,2-dicarboxylic acid withbrucine according to the method reported by J. J. Gajewski in J. Am.Chem. Soc., 93, 4450-8 (1971).

EXAMPLE 31

[1'S,2'S,3'S]-9-(2',3'-Bis(hydroxymethyl)cyclobutyl)adenine

Following the procedures described in Example 26, replacing the productof Step G of Example 25 with[1S,2D,3S]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylaminefrom Example 30, the desired product is obtained with both hydroxylgroups protected with t-butyldimethylsilyl groups. The protecting groupsare removed as described in Step E of Example 1.

EXAMPLE 32 [1'S,2'S,3'S]-1-(2',3'-Bis(hydroxymethyl)cyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with[1S,2D,3S]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylaminefrom Example 25, the title compound is prepared.

EXAMPLE 33 [1'S,2'S,3'S]-1-(2',3'-Bis(hydroxymethyl)cyclobutyl)thymine

Following the procedures in Example 2, replacing, in Step A, the productof Step D of Example 1 with[1S,2S,3S]-2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylaminefrom Example 25, and replacing, in Step B, (E)-3-ethoxyacryloyl chloridewith 3-methoxymethacryloyl chloride, the title compound is prepared.

EXAMPLE 34 [1'S,2'S,3'S]-1-(2',3'-Bis(hydroxyemthyl)cyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 32, the titlecompound is prepared.

EXAMPLE 35 9-(2'-Hydroxymethyl-1'-cyclobutyl)guanine Step A: Methyl1-cyclobutenecarboxylate

A solution of 1-cyclobutenecarboxylic acid, prepared as described by W.G. Dauben and J. R. Wiseman, J Am Chem Soc, 89, 3545 (1967), in 75 mL ofdiethyl ether was treated with a freshly prepared and distilled solutionof diazomethane in diethyl ether. The ether solution of diazomethane wasadded until a yellow color persisted in the reaction solution. Thereaction solution was purged with nitrogen and concentrated in vacuo at40° C. to give crude methyl 1-cyclobutenecarboxylate in quantitativeyield. The product was taken on to the next step without purification; ¹H NMR (CDCl₃) δ 2.49 (dt, 2H), 2.73 (t, 2H), 3.72 (s, 3H), 6.79 (t, 1H).

Step B: 2-Amino-6-chloro-9-(2'-methoxycarbonyl-1'-cyclobutyl)purine

Methyl 1-cyclobutenecarboxylate (0.28 g, 2.5 mmol) from Step A wascombined under a nitrogen atmosphere with 606 mg (3.6 mmol) of2-amino-6-chloropurine and 53 μL (0.36 mmol) of1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in 75 mL of acetonitrile. Afterstirring for 66 h at ambient temperature, a second 53 μL aliquot of DBUwas added and stirring continued. After a total of 36 h, the reactionwas quenched by the addition of 0.28 mL of glacial acetic acid and thereaction mixture was concentrated in vacuo. The residue (2.43 g) wasdissolved in approximately 3 mL of methylene chloride and purified on a1.8×47 cm silica gel column eluted @ 2-3 psi with the followingstep-wise solvent gradient: 1). 250 mL of methylene chloride, 2). 250 mLof 2% methanol in methylene chloride, 3). 250 mL of 4% methanol inmethylene chloride and 4). 250 mL of 6% methanol in methylene chloride,to give 715 mg (71% yield) of the title compound as a mixture of cis andtrans isomers. Equilibration to the desired trans isomer was achieved bytreating the mixture of isomers 455 μL of DBU in 35 mL of acetonitrileat 45° C., under nitrogen, for 42 h. The reaction mixture wasconcentrated in vacuo and the residue was dissolved in approximately 2mL of methylene chloride and purified on a 1.5×45 cm silica gel columneluted @ 5 psi with a step-wise solvent gradient of 200 mL of methylenechloride followed by 200 mL of 2% methanol in methylene chloride and 200mL of 4% methanol in methylene chloride to give 608 mg (87% yield) ofthe desired trans iaomer of the title compound. MS DCI-NH₃ M/Z: 282 and284 (M+H)⁺.

Step C: 2-Amino-6-chloro-9-(2'-hydroxymethyl-1'-cyclobutyl)-purine

2-Amino-6-chloro-9-(2'-methoxycarbonyl-1'-cyclobutyl)purine (605 mg,2.15 mmol) from Step B was dissolved in 250 mL of freshly distilled dryTHF and the solution was cooled to 0° C. under a nitrogen atmosphere.Lithium aluminum hydride (122 mg, 3.2 mmol) was added in one portion andthe reaction mixture was stirred at 0° C. (under a nitrogen atmosphere)for 0.5 h. The reaction was then quenched by the addition of 122 μL ofwater, followed by 122 μL of 15% sodium hydroxide and 366 μL of water.The reaction mixture was filtered and the filter cake was washed withethyl acetate. The filtrate was concentrated in vacuo to give 490 mg(90% yield) of the title compound; MS DCI-NH₃ M/Z: 254 and 256 (M+H)⁺.

Step D: 9-(2'-Hydroxymethyl-1'-cyclobutyl)guanine

2-Amino-6-chloro-9-(2'-hydroxymethyl-1'-cyclobutyl)purine (490 mg, 22.5mmol) from Step C and 100 mL of 1M hydrochloric acid solution werecombined and heated at reflux under nitrogen for approximately 5 h. Thereaction mixture was concentrated in vacuo at 45°-50° C. The residue wasazeotropically distilled three times with 25 mL of absolute ethanol andthe resultant residue (543 mg) was dissolved in 5 mL of water. Theaqueous solution was neutralized with concentrated ammonium hydroxidesolution and concentrated in vacuo. The residue (594 mg) was dissolvedin 180 mL of 50% aqueous ethanol and the resultant solution was heatedto 70° C., treated with 50 mg Darco G-60 charcoal, filtered andconcentrated to approximately 35 mL @80° C. This solution was allowed tocool to 3° C. slowly overnight and the crystals were collected bysuction filtration to give 336 mg (74% yield) of the title compound; MSDCI-NH₃ M/Z: 236 (M+H)⁺ ; ¹ H NMR (d6-DMSO) δ 1.60 (m, 1H), 1.85 (m,1H), 2.20-2.40 (m, 2H), 2.98 (m, 1H), 3.42 (t, 2H), 4.51 (q, 1H), 7.88(s, 1H); Analysis calculated for C₁₀ H₁₃ N₅ O₂ : C, 51.05; H, 5.57; N,29.77. Found: C, 51.07; H, 5.63; N, 29.65.

EXAMPLE 36 9-(2'-hydroxymethyl-1'-cyclobutyl)adenine Step A:9-(2-methoxycarbonyl-1-cyclobutyl)adenine

Adenine (486 mg, 3.6 mmol) was combined with an excess of methyl1-cyclobutene carboxylate (˜25 mmol) from Step B of Example 35 and 53 μL(0.36 mmol) of DBU in 75 mL of acetonitrile and the mixture was stirredat ambient temperature, under a nitrogen atmosphere. After 66 h, asecond 53 μL aliquot of DBU was added and stirring continued. After atotal of 136 h, the reaction was quenched by the addition of 0.28 mL ofglacial acetic acid and concentrated in vacuo. The residue was dissolvedin approximately 3 mL of methylene chloride and purified on a 1.5×45 cmsilica gel column eluted @ 5-10 psi with a step-wise solvent gradient ofmethanol in methylene chloride, starting with 100% methylene chlorideand increasing in 2% steps to 8% methanol, each step was 200 mL ofsolvent. The title compound was obtained in 61% yield (542mg) as amixture of cis and trans isomers and equilibrated to the desired transisomer by treating the mixture of isomers with 394 μL of DBU in 35 mL ofacetonitrile at 45° C., under nitrogen, for 46 h. The reaction mixturewas concentrated in vacuo and the residue was dissolved in approximately2 mL of methylene chloride and purified on a 1.5×45 cm silica gel columneluted @5 psi with a step-wise solvent gradient of 200 mL of methylenechloride followed by 200 mL of 5% methanol in methylene chloride and 200mL of 7% methanol in methylene chloride to give 502 mg (57% yield) ofthe desired trans isomer of the title compound; ¹ H NMR (CD₃ OD) δ 2.11(m, 1H), 2.30 (m, 1H), 2.45 (m, 1H), 2.77 (m, 1H), 3.68 (s, 3H), 4.01(m, 1H), 5.18 (q, 1H), 8.20 (s, 1H), 8.25 (s, 1H); MS DCI-NH₃ M/Z: 248(M+H)⁺.

Step B: 9-(2-hydroxymethyl-1-cyclobutyl)adenine

9-(2-methoxycarbonyl-1-cyclobutyl)adenine (500 mg, 2.02 mmol) from StepA was dissolved in 250 mL of THF and the solution was cooled to 0° C.with stirring under a nitrogen atmosphere. Lithium aluminum hydride (115mg, 3.03 mmol) was added and the reaction mixture was stirred for 30minutes then quenched with 115 μL of water followed by 115 μL of 15%sodium hydroxide and 345 μL of water. The reaction mixture was filteredthrough Celite filter aid. The Celite was washed with ethyl acetate andthe filtrater concentrated in vacuo to give 430 mg (97% yield) of thetitle compound; MS DCI-NH₃ M/Z: 220 (M+H)⁺ ; ¹ H NMR (d6-DMSO) δ 1.65(m, 1H), 1.90 (m, 1H), 2.32 (m, 1H), 2.50 (m, 1H), 3.10 (m, 1H), 3.47(t, 2H), 4.67-4.77 (m, 2H, H-1'+OH), 7.20 (bs, 2H), 8.12 (s, 1H), 8.27(s, 1H); Analysis calculated for C₁₀ H₁₃ N₅ O: C, 54.78; H, 5.98; N,31.95. Found: C, 54.79; H, 6.01; N, 31.66.

EXAMPLE 37 1-(2'-Hydroxymethyl-1'-cyclobutyl)uracil

Following the procedures in Example 36, replacing adenine with uracil,the title compound is prepared.

EXAMPLE 38 1-(2'-Hydroxymethyl-1'-cyclobutyl)thymine

Following the procedures in Example 36, replacing adenine with thymine,the title compound is prepared.

EXAMPLE 39 1-(2'-Hydroxymethyl-1'-cyclobutyl)cytosine

Following the procedures in Example 36, replacing adenine with cytosine,the title compound is prepared.

EXAMPLE 40 9-(2'-(Hydroxymethyl)-3'-methylcyclobutyl)guanine Step A:9-(2'-(Hydroxymethyl)-3'-((2"-pyridyl)mercaptomethyl)-cyclopropyl)guanine

9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine (1.5 g, 5.6 mmol),prepared as described in Example 1, 1.25 g (5.6 mmol) of 2,2'-dipyridyldisulfide (Aldrithiol-2® commercially available from Aldrich ChemicalCompany) and 5.7 g (28.3 mmol) of tri-n-butylphosphine were combined in50 mL of pyridine and the reaction mixture was stirred at ambienttemperature, under a nitrogen atmosphere, for 16 h. At this time somestarting materials were still unreacted according to TLC analysis onsilica gel plates eluted with 20% methanol in methylene chloride, and anadditional 400 mg of Aldrithiol-2® was added and stirring continued.After a total of 41 h, the reaction was quenched with methanol andevaporated in vacuo. The residue was dissolved in 5 mL of methylenechloride and purified on a 3×50 cm silica gel column eluted at 2-3 psiwith a solvent gradient of methanol in methylene chloride as follows:750 mL of 5% methanol in methylene chloride followed by 1 L of 10%methanol in methylene chloride, followed by 1 L of 15% methanol inmethylene chloride and finally 2 L of 20% methanol in methylenechloride, to give 63 mg (3% yield) of the title compound; ¹ H NMR(CD30D) δ (2.3-3.4, m, 2H), 2.62 (m, 1H), 2.83 (m, 1H), 3.4-3.5 (m, 2H),3.6-3.75 (m, 2H), 7.1 (m, 1H), 7.3 (m, 1H), 7.6 (m, 1H), 7.84 (s, 1H),8.4 (m, 1H); MS DCI-NH₃ M/Z: 359 (M+H)⁺.

Step B: 9-(2'-(Hydroxymethyl)-3'-methylcyclopropyl)guanine

9-(2'-(Hydroxymethyl)-3'-((2"-pyridyl)mercaptomethyl)cyclobutyl)guanine(60 mg, 0.17 mmol) from Step A was dissolved in 5 mL of ammonia at -78°C. and sodium metal was added until a persistent blue color was observed(˜100 mg of sodium). The reaction mixture was stirred at -78° C. under anitrogen atmosphere for 0.5 h and then quenched with approximately 50 mgof solid ammonium chloride. The ice bath was removed and ammonia gas wasswept out of the reaction mixture with nitrogen. The residue wassuspended in approximately 2 mL of water and purified on a 1.0×45 cmreverse phase column of Bondesil® C18 (40 μm particles) packed withmethanol, equilibrated with 100 mL of water @ 10 psi and eluted @ 10 psiwith 50 mL of water, followed by 50 mL of 10% aqueous methanol, followedby 20% aqueous methanol and finally 30% aqueous methanol to give 22 mg(52% yield) of the title compound; DCI-NH₃ MS M/Z: 250 (M+H)⁺ ; ¹ H NMR(d6-DMSO) δ 1.14 (d, 3H), 1.87-1.97 (m, 2H), 2.45 (m, 2H), 3.45 (t, 2H),4.32 (q, 1H), 7.79 (s, 1H).

EXAMPLE 41 9-(2'-(Hydroxymethyl)-3'-methylcyclobutyl)adenine

Following the procedures described in Example 40, replacing9-(2',3'-bis(hydroxymethyl)-cyclobutyl)guanine, the product of Example1, with 9-(2',3'-bis(hydroxymethyl)cyclobutyl)adenine, Example 4, thetitle compound is prepared.

EXAMPLE 42 9-(2'-Hydroxy-3'-hydroxymethyl-1'-cyclobutyl)guanine Step A:2,3-Bis(((1.1-dimethylethyl)dimethyl)oxymethyl)-1-methylenecyclobutane

1,2-Bis(hydroxymethyl)-3-methylenecyclobutane (29.9 g, 233 mmol),obtained from Step A of Example 1, and t-butyldimethylsilyl chloride(140 g, 900 mmol) were combined in 800 mL of anhydrous pyridine and thereaction mixture was stirred at ambient temperature overnight under anitrogen atmosphere. The reaction was quenched with 20 mL of methanoland the reaction mixture concentrated under reduced pressure to a syrup.The syrup was dissolved in 1 L of methylene chloride and the solutionwashed with 5% aqueous sodium bicarbonate solution (3×300 mL), driedover anhydrous magnesium sulfate, filtered and concentrated underreduced pressure. The syrup-like residue (105 g) was purified on a4.8×20 cm silica gel column packed with hexane and eluted @ 1-2 psi with1 L of hexane to give 78.6 g (95% yield) of the title compound; MSDCI-NH₃ M/Z: 357 (M+H)+, 374 (M+NH₄)+; ¹ H NMR (CDCl₃) δ 0.05 (s, 12H),0.90 (s, 18H), 2.20 (m, 1H), 2.40 (m, 1H), 2.60 (m, 1H), 2.82 (m, 1H),3.60-3.70 (m, 4H), 4.76 (q, 1H), 4.84 (q, 1H).

Step B: 2,3-Bis(((1,1-dimethyl)dimethylsilyl)oxymethyl)cyclobutanone

2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-methylene-cyclobutane(30 g, 82 mmol) from Step A was dissolved in a mixture of 600 mL ofmethylene chloride and

150 mL of methanol and this mixture was cooled to -78° C. Ozone wasbubbled through the reaction mixture at -78° C. until a persistent bluecolor was observed (approximately 4.5 h). Nitrogen was then bubbledthrough the reaction mixture until it became colorless. To thiscolorless solution was added 50 mL of dimethyl sulfide and stirring wascontinued at -78° C. for 15 minutes. The reaction mixture was allowed tostand overnight at 0° C. and then carefully concentrated under reducedpressure. The syruplike residue (72.7 g) was purified on a 2.5×40 cmsilica gel column eluted @5 psi with 1.1 L of hexane to give 10.2 g (35%yield) of the title compound as a syrup; IR (CDCl₃ solution) 1778 (C═O),1055 (C--O) cm⁻¹ ; ¹ H NMR (CDCl₃) δ 0.05 (d, 12H), 0.85 (d, 18H), 2.64(m, 1H), 2.88 (m, 1H), 3.18 (m, 1H), 3.65 (dd, 1H), 3.75 (t, 2H), 3.86(dd, 1H); MS DCI-NH₃ M/Z: 359 (M+H)+, 376 (M+NH₄)⁺.

Step C: 2.3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanol

2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanone (10.2g, 28.4 mmol) from Step B was dissolved in tetrahydrofuran (THF) and thesolution was cooled to -78° C. under a nitrogen atmosphere. To the THFsolution at -78° C. was slowly added, with stirring, 31 mL (31 mmol) ofpotassium tri-sec-butylborohydride (sold by Aldrich Chemical Company asa 1M solution in THF under the registered trademark K-Selectride®).After stirring for 0.5 h at -78° C., the reaction mixture was allowed towarm to 0° C. and it was stirred for 40 minutes at 0° C. One equivalent(1.9 mL) of glacial acetic acid was added and the reaction mixture wasconcentrated in vacuo to approximately 50 mL. The concentrate wasdiluted with 1 L of methylene chloride and the resultant solution waswashed with 400 mL of 5% aqueous sodium bicarbonate solution, dried overanhydrous magnesium sulfate, filtered and concentrated to a syrup. Thesyrup (15.5 g) was chromatographed on a 4.5×45 cm silica gel columneluted @ 2-5 psi with 2 L of methylene chloride. All fraction containingthe desired product were combined and concentrated. The residue (10 g)was rechromatographed as described above to give 6.3 g (62% yield) ofthe title compound as a syrup; ¹ H NMR (CDCl₃) δ 0.07 (d, 12H), 0.92 (d,18H), 2.01 (m, 1H), 2.13 (m, 2H), 2.25 (m, 1H), 2.40 (m, 1H), 3.35 (d,1H), 3.55 (m, 2H), 3.86 (dd, 1H), 3.98 (dd, 1H); MS DCI-NH₃ M/Z: 361(M+H)⁺.

Step D: 2,3-Bis(hydroxymethyl)cyclobutanol

2,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanol (6.3 g,17.5 mmol) from Step C was combined with 5.3 mL (43 mmol) ofchlorotrimethyl-silane in 103 mL of methanol. The reaction mixture wasstirred at ambient temperature under a nitrogen atmosphere for 0.5 hthen concentrated under reduced pressure to an oil. Residualchlorotrimethylsilane was removed by co-evaporation with methanol (3×30mL) to give title compound in quantitative yield and this crude productwas carried on to the next step without purification; ¹ H NMR (CD₃ OD) δ1.94-2.14 (m, 2H), 2.17-2.37 (m, 2H), 3.53 (d, 2H), 3.68 (dd, 1H), 3.85(dd, 1H), 4.39 (m, 1H); MS DCI-NH₃ M/Z: 133 (M+H)⁺, 150 (M+NH₄)⁺.

Step E: 7-Hydroxymethyl-3-phenyl-2,4 dioxabicyclo[2.4.0]octane

2,3-Bis(hydroxymethyl)-cyclobutanol (17.5 mmol) from Step D and 2.7 g(17.5 mmol) of benzaldehyde dimethyl acetal were combined in a mixtureof 30 mL of freshly distilled methylene chloride and 30 mL of freshlydistilled THF. The reaction mixture was stirred at ambient temperaturefor 1.5 h under a nitrogen atmosphere and then an additional 1 mL ofbenzaldehyde dimethyl acetal was added. After stirring the reactionmixture for 2 h, 100 mL of 5% aqueous sodium bicarbonate solution wasadded. The resultant aqueous solution was extracted with 250 mL ofmethylene chloride. The organic phase was dried over anhydrous magnesiumsulfate, filtered and concentrated in vacuo. The residue (4.5 g) wasdissolved in 5-10 mL of methylene chloride and purified on a 2.5×40 cmsilica gel column eluted @ 5 psi with 500 mL of methylene chloridefollowed by 500 mL of 4% methanol in methylene chloride to give 2.85 g(74% yield) of the title compound as a syrup; MS DCI-NH₃ M/Z: 221 (M+H)⁺; ¹ H NMR (CDCl₃) δ 1.91-2.09 (m, 2H), 2.18 (m, 1H), 3.17 (m, 1H), 3.71(m, 1H), 4.03 (d, 2H), 4.59 (t, 1H), 5. 36 (s, 1H), 7.35 (m, 3H), 7.52(dd, 2H).

Step F: 1-Benzoyloxy-2-bromomethyl-3-hydromethylcyclobutane

7-Hydroxymethyl-3-phenyl-2,4-dioxabicyclo[2.4.0]octane (2.85 g, 12.9mmol) from Step E was combined with 2.6 g (14.6 mmol) ofN-bromosuccinimide and 3.5 g (17.7 mmol) of barium carbonate in1,2-dichloroethane which had been dried over molecular sieves. Thereaction mixture was heated to reflux under a nitrogen atmosphere for 1h. The reaction mixture was filtered and the filtrate diluted with 100mL of methylene chloride, washed with 100 mL of 5% aqueous sodiumcarbonate and 100 mL of water, dried over anhydrous magnesium sulfateand concentrated. The residue was dissolved in approximately 2 mL ofmethylene chloride and purified on a 1.5×40 cm silica gel column eluted@ 5 psi with 100 mL of methylene chloride, followed by 200 mL of 1%methanol in methylene chloride and 200 mL of 2% methanol in methylenechloride to give 2.5 g (65% yield) of the title compound as a syrup; ¹ HNMR (CDCl₃) δ 2.33 (m, 2H), 2.50 (m, 1H), 3.60 (t, 2H), 3.18-3.31 (m,3H), 5.41 (m, 1H), 7. 47 (m, 2H), 7.59 (m, 1H), 8.05 (m, 2H); MS DCI-NH₃M/Z: 299 and 301 (M+H)⁺, 316 and 318 (M+NH₄)⁺.

Step G: 1-Benzoyloxy-3-hydroxymethyl-2-methylenecyclobutane

1-Benzoyloxy-2-bromomethyl-3-hydroxymethylcyclobutane (2.5 g, 8.36 mmol)from Step F and tetra-n-butylammonium fluoride ((8.1 g, 25 mmol) werecombined in 200 mL of freshly distilled THF and the reaction mixture wasstirred at ambient temperature, under a nitrogen atmosphere, overnight.The volume of the reaction mixture was then reduced to 25 mL and thiswas dissolved in 250 mL of methylene chloride. The methylene chloridesolution was washed with 150 mL of water, dried over anhydrous magnesiumsulfate, filtered and concentrated under reduced pressure. The residue(4.9 g) was dissolved in ˜5 mL of methylene chloride and purified on a2.5×35 cm silica gel column eluted @ 5 psi with a step-wise (4×200 mLsteps) of methanol in methylene chloride from 0% to 3% methanol to give1.54 g (85% yield) of the title compound as a syrup; ¹ H NMR (CDCl₃) δ2.38 (m, 2H), 3.22 (m, 1H), 3.69-3.85 (m, 2H), 5.13 (t, 1H), 5.32 (t,1H), 5.79 (M, 1H), 7.45 (m, 2H), 7.58 (m, 1H), 8.08 (m, 2H); MS DCI-NH₃M/Z: 219 (M+H)⁺, 236 (M+NH₄)⁺.

Step H: 2-Benzoyloxy-4-hydroxymethylcyclobutanone

A mixture of 2.09 g (9.5 mmol) of1-benzoyloxy-3-hydroxymethyl-2-methylenecyclobutane from Step G, 112 mLof methylene chloride and 28 mL of methanol was cooled to -78° C. undera nitrogen atmosphere. Ozone was bubbled through the mixture for 10minutes, until a persistent blue color was observed. Excess ozone wasflushed out with nitrogen, 9 mL of dimethyl sulfide was added and thereaction mixture stirred for 0.5 h at -78° C. The reaction mixture wasallowed to warm to ambient temperature, stirred for 0.5 h at ambienttemperature and evaporated under reduced pressure to a syrup. The syrup(2.5 g) was dissolved to ˜2 mL of methylene chloride and purified on a1.5×45 cm silica gel column eluted @ 5 psi with 100 mL of methylenechloride, followed by 250 mL of 1% methanol in methylene chloride and250 mL of 2% methanol in methylene chloride to give 1.79 g (86% yield)of the title compound; MS DCI-NH₃ M/Z: 221 (M+H)⁺, 238 (M+NH₄)⁺.

Step I: 2-Benzoyloxy-4-hydroxymethylcyclobutanol

Glacial acetic acid in (25 mL) a 250 mL 3-neck flask was cooled in anice bath under a stream of nitrogen. Sodium borohydride was addedcautiously in portions over a 5 minute period. The ice bath removed andthe reagent was used after stirring for 15 minutes at ambienttemperature. 2-Benzoyloxy-4-hydroxymethylcyclobutanone (1.43 g, 6.5mmol) from Step H was dissolved in 45 mL of glacial actetic acid andimmediately treated with the above borohydride reagent. After stirringthe reaction mixture for 35 minutes, the reaction was quenched with ˜2mL of methanol and the reaction mixture was concentrated in vacuo to asyrup. The syrup was dissolved in 250 mL of ethyl acetate and the ethylacetate solution was washed with water and 5% aqueous sodiumbicarbonate, dried over magnesium sulfate, filtered and concentrated togive 1.47 g of the title compound which was taken on to the next stepwithout purification; MS DCI-NH₃ M/Z: 221 (M+H)⁺, 238 (M+NH₄)⁺.

Step J:2-Benzoyloxy-1-(((1,1-dimethylethyl)diphenylsilyl)oxy)-4-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutane

2-Benzoyloxy-4-hydroxymethylcyclobutanol (1.9 g, 8.5 mmol) from Step I,t-butyldiphenylsilyl chloride (5.2 g, 18.6 mmol) and imidazole (2.6 g,37.6 mmol) were combined in 140 mL of N,N-dimethylformamide (DMF) andthe reaction mixture was stirred at ambient temperature for 64 h under anitrogen atmosphere. The reaction mixture was concentrated in vacuo andthe residue dissolved in 250 mL of diethyl ether. The ether solution waswashed with 3×100 mL of water, dried over anhydrous magnesium sulfate,filtered and concentrated under reduced pressure. The residue (6.8 g)was dissolved in 10 mL of hexane and purified on a 2.8×54 cm silica gelcolumn eluted at 5 psi with a step-wise solvent gradient of acetone inhexane of 4×1% steps @ 500 mL each, from 1% to 4% acetone. The titlecompound was obtained (4.22 g) in 72% yield; MS DCI-NH₃ M/Z: 716(M+NH₄)⁺ ; ¹ H NMR (CDCl₃) δ 1.89-2.10 (m, 2H), 2.75 (m, 1H), 3.30 (ddd,2H), 4.40 (t, 1H), 5.24 (m, 1H), 7.20-7.70 (m, 23H +CHCl₃), 8.23 (m,2H).

Step K:2-O-((1,1-dimethylethyl)diphenylsilyl)-3-(((1,1dimethylethyl)-diphenylsilyl)oxymethyl-1,2-cyclobutanediol

2-Benzoyloxy-1-(((1,1-dimethylethyl)diphenylsilyl)oxy)-4-(((1,1-dimethyl-ethyl)diphenylsilyl)oxymethyl)cyclobutane(4.2 g, 6.0 mmol) from Step J was dissolved in freshly distilled THF andthe resultant solution was cooled to -78° C., with stirring, under anitrogen atmosphere. Lithium triethylborohydride (20 mL of a 1M solutionin THF, 20 mmol) was added and the reaction mixture was allowed to warmto 0° C. After stirring at 0° C. for 0.5 h, the reaction mixture wascooled to -78° C. and quenched with 1.2 mL of glacial acetic acid andconcentrated in vacuo. The residue was triturated with ˜50 mL of hexane,filtered and suspended in hexane. The suspension was applied to a 2.8×55cm silica gel column which was eluted @ 2 psi with 1 L of 2% acetone inhexane to give 2.3 g (64% yield) of the title compound; ¹ H NMR (CDCl₃)δ 1.88 (m, 2H), 2.54 (m, 1H), 2.97 (d, 1H), 3.24-3.39 (ddd, 2H), 4.15(m, 1H), 4. 24 (t, 1H); MS DCI-NH₃ M/Z: 595 (M+H)⁺, 612 (M+NH.sub. 4)⁺.

Step L:1-O-methanesulfonyl-2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)di-phenylsilyl)oxymethyl)-1-cyclobutanol

Freshly distilled triethylamine (1.28 g, 8.2 mmol) was dissolved in 75mL of freshly distilled methylene chloride. To this solution was added2.3 g (3.9 mmol) of 2-O-((1,1-dimethylethyl)diphenylsilyl)-3-(((1,1-dimethylethyl)diphenyl-silyl)oxymethyl)-1,2-cyclobutanediol from Step Kand the resultant solution was cooled to -78° C. with stirring, under anitrogen atmosphere. Methanesulfonyl chloride (0.99 g, 8.2 mmol) wasadded and the reaction mixture was allowed to warm to ambienttemperature. After 3.5 h, the reaction mixture was diluted with 125 mLof methylene chloride and this solution was washed with 100 mL of water,dried over anhydrous magnesium sulfate, filtered and concentrated invacuo. The residue (2.9 g) was dissolved in 25 mL of 10% acetone inhexane and purified on a 2.5×45 cm silica gel column eluted at 2 psiwith 500 mL of 5% acetone in hexane, followed by 250 mL of 10% acetonein hexane, to give 1.57 g (60% yield) of the title compound; MS DCI-NH₃M/Z: 690 (M+NH₄)⁺ ; ¹ H NMR (CDCl₃) δ 1.95, m, 1H), 2.20 (m, 1H), 2.77(m, 1H), 2.90 (s, 3H), 3.39 (d, 2H), 4.39 (m, 1H), 4.88 (m, 1H),7.30-7.54 (m, 15H), 7.60-7.70 (m, 5H).

Step M:2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1',1'-dimethylethyl)-diphenylsilyl)oxymethyl)-1-azidocyclobutane

1-O-methanesulfonyl-2-(((1,1-dimethylethyl)-diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)-1-cyclobutanol(1.57 g, 2.3 mmol) from Step L and lithium azide (0.69 g, 14.1 mmol)were combined in 40 mL of anhydrous DMF. The reaction mixture washeated, with stirring, in an oil bath at 90° C. After stirring for 22.5h at 90° C. the temperature was reduced to 80° C. and the reactionmixture was stirred at 80° C. for 16.5 h. The DMF was removed in vacuo @50° C. The residue was dissolved in 200 mL of diethyl ether and theether solution was washed with 100 mL of 5% aqueous sodium bicarbonatesolution and 100 mL of water, dried over anhydrous magnesium sulfate,filtered and concentrated under reduced pressure. The residue (1.34 g)was dissolved in 25 mL of 10% acetone in hexane solution and purified ona 1.5×45 cm silica gel column eluted at 2 psi with 150 mL of hexane,followed by 300 mL of 3% acetone in hexane, to give 812 mg (56% yield)of the title compound; MS DCI-NH₃ M/Z: 637 (M+NH₄)⁺ ; ¹ H NMR (CDCl₃) δ1.47 (m, 1H), 1.97-2.12 (m, 2H), 3.39 (d, 2H), 3.49 (m, 1H), 4.11 (t,1H), 7.30-7.55 (m, 15H), 7.60-7.70 (m, 5H).

Step N:2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)-diphenylsilyl)oxymethyl)-1-aminocyclobutane

2-(((1,1-dimethylethyl)diphenylsilyloxy)-3-(((1,1-dimethylethyl)diphenyl-silyl)oxymethyl)-1-azidocyclobutane(800 mg, 1.29 mmol), the product of Step M, was dissolved in 20 mL ofmethanol. To this solution was added 200 mg of 5% palladium on carbon,followed by 420 mg of ammonium formate. The flask was stoppered and thereaction mixture was stirred at ambient temperature for 23 h. Thereaction mixture was filtered and the filtrate concentrated underreduced pressure. The residue was dissolved in 200 mL of diethyl etherand the ether solution was washed with 100 mL of 5% aqueous sodiumbicarbonate solution, dried over anhydrous magnesium sulfate, filteredand concentrated under reduced pressure to give 707 mg (92% yield) ofthe title compound; MS DCI-NH₃ M/Z: 594 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ0.88-1.08 (m, 18H), 1.95-2.15 (m, 3H), 3.01 (q, 1H), 3.5 (m, 2H), 3.68(t, 1H).

Step O:2-Amino-4-hydroxy-5-nitro-6-(2'-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3'-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutylamino)pyrimidine

2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)diphenyl-silyl)oxymethyl)-1-aminocyclobutane (588 mg, 0.99mmol), the product of Step N, 189 mg (0.99 mmol) of2-amino-6-chloro-4-hydroxy-5-nitropyrimidine (prepared as described byJ. F. Constant, et al. in J. Heterocyclic Chem, 1035 (1985)) andtriethylamine (220 μL, 1.50 mmol) were combined in 5 mL of anhydrousDMF. The reaction mixture was stirred in an oil bath at 50° C. under anitrogen atmosphere for 2.5 h. Diethyl ether (200 mL) was added and theether solution was washed with 2×50 mL of water, dried over anhydrousmagnesium sulfate, filtered and concentrated in vacuo. The residue (800mg) was dissolved in methylene chloride and purified on a 1.0×45 cmsilica gel column eluted @ 10 psi with 100 mL of methylene chloride,followed by 100 mL of 2% methanol in methylene chloride and finally 100mL of 4% methanol in methylene chloride, to give 473 mg (64% yield) ofthe title compound; MS DCI-NH₃ M/Z: 748 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ2.13-2.33 (m, 3H), 2.89 (s, 1H), 2.97 (s, 1H), 3.59-3.70 (m, 2H), 4.26(t, 1H), 4.65 (m, 1H), 7.30-7.47 (m, 10H), 7.56-7.60 (m, 10H).

Step P: 9-(2'-hydroxy-3'-hydroxymethyl-1'-cyclobutyl)guanine

2-Amino-4-hydroxy-5-nitro-6-(2'-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3'-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutylamino)pyrimidine (470mg, 0.63 mmol), the product of Step O, was dissolved in warm, degassedformic acid, under an argon atmosphere and the resultant solution wasstirred at ambient temperature. Zinc dust (1.57g, 24 mmol) was added inone portion and stirring was continued. After approximately 3 h, thereaction mixture was filtered through a millipore 0.45 μ filter. Thesolid was washed with formic acid . The formic acid solution (40 mL) washeated in a bomb under argon for 3 h at 130° C. and then evaporated invacuo. The residue was suspended in 15 mL of water and concentrated invacuo three times. The residue was then resuspended in 20 mL of water(pH of aqueous solution ˜6) and the suspension was filtered by suction.The filter cake was dissolved in 10 mL of concentrated ammoniumhydroxide solution and this solution was concentrated in vacuo. Theresidue from the ammonia solution was then suspended in water andreconcentrated. The residue (238 mg) was dissolved in 45 mL of water andtreated with ˜50 mg of Darco G-60® activated charcoal at 50°-60° C. Thecharcoal was filtered while the suspension was still hot and washed withwater. The filtrate was concentrated in vacuo @85° C. and the residuewas redissolved in 25 mL of water. The aqueous solution was allowed tocool slowly overnight, then it was cooled to 3° C. for 1-2 h. The firstcrop of crystals were collected by suction filtration and dried in vacuoat 45° C. to give mg (53% yield) of the title compound; MS DCI-NH₃ M/Z:252(M+H)⁺, 269 (M+NH₄)⁺ ; ¹ H NMR (d6-DMSO) δ 1.65 (q, 1H), 2.00 (m,1H), 2.19 (q, 1H), 3.55 (m, 2H), 4.17 (q, 1H), 4.29 (q, 1H), 4.56 (t,1H-OH), 5.55 (d, 1H-OH), 6.40 (bs, H, NH2), 7.70 (s, 1H).

EXAMPLE 43 9-(2'-Hydroxy-3'-hydroxymethyl-1'-cyclobutyl)adenine

Following the procedures in Example 4, replacing the product of Step Eof Example 1 with2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)-1-aminocyclobutane,the product of Step N of Example 42, the title compound is prepared withthe hydroxyl groups protected with the t-butyldiphenylsilyl group. Theprotecting groups are removed as described by S. Hanessian and P.Lavallee in Canadian J. Chem, 53, 2975-7 (1975).

EXAMPLE 44 1-(2'-Hydroxy-3'-hydroxymethyl-1'-cyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)diphenyl-silyl)oxymethyl)-1aminocyclobutane,the product of Step N of Example 42, the title compound is prepared.

EXAMPLE 45 1-(2'-Hydroxy-3'-hydroxymethyl-1'-cyclobutyl)thymine

Following the procedures described in Example 2, replacing, in Step A,the product of Step D of Example 1 with2-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)-1-aminocyclobutane,the product of Step N of Example 42, and replacing, in Step B,(E)-3-ethoxyacryloyl chloride with 3-methoxymethacrylic acid chloride,the title compound is prepared.

EXAMPLE 46 1-(2'-Hydroxy-3'-hydroxymethyl-1'-cyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 44, the titlecompound is prepared.

EXAMPLE 47 9-(3,3-Bis(hydroxymethyl)-cyclobutyl)guanine Step A:3.3-Bis(hydroxymethyl)-1,1-dimethoxycyclobutane

Diisopropyl 3,3-dimethoxy-cyclobutane-1,1-dicarboxylate (6.0 g, 20.8mmol), prepared as described by P. E. Pigou and C. H. Schiesser, J OrgChem, 53, 3841-3 (1988), was dissolved in 200 mL of anhydrous diethylether and the ether solution was cooled to 0° C. with stirring under anitrogen atmosphere. Lithium aluminum hydride (1.6 g, 42 mmol) was addedto the ether solution in portions and the reaction mixture was stirredat 0° C. for 0.5 h. The reaction was then quenched by the addition of1.6 mL of water, followed by 1.6 mL of 15% aqueous sodium hydroxidesolution and 4.8 mL of water. The reaction mixture was filtered, thefilter cake washed with diethyl ether and the combine ether filtrateswere concentrated under reduced pressure. The residue (3.0 g) wasdissolved in 2 mL of methylene chloride and purified on a 1.5×45 cmsilica gel column eluted @ 2-3 psi with 200 mL of acetone:hexane (1:2v/v), followed by 200 mL of acetone:hexane (1:1 v/v) to give 1.51 g (41%yield) of the title compound; MS DCI/NH₃ M-Z: 194 (M+NH₄)⁺ ; ¹ H NMR(CDCl₃) δ 1.99 (s, 4H), 2.35 (t, 2H-OH), 3.16 (s, 6H), 3.77 (d, 4H).

Step B:3,3-Bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanone-O-methyloxime

3,3-Bis(hydroxymethyl)-1,1-dimethoxycyclobutane (1.35 g, 7.65 mmol) fromStep A and 3.8 mL of 2M aqueous hydrochloric acid solution were added to60 mL of THF and the reaction mixture was stirred at ambient temperaturefor 0.5 h, under a nitrogen atmosphere. The reaction mixture wasneutralized by the addition of a strongly basic hydroxide resin thenfiltered and concentrated in vacuo. The residue was washed with THF anddissolved in 30 mL of anhydrous pyridine. To this solution was added 767mg (9.2 mmol) of methoxylamine hydrochloride and the resultant solutionwas stirred for ˜20 h at ambient temperature, under a nitrogenatmosphere. t-Butyldimethylsilyl chloride (3.5 g, 23 mmol) and 60 mL ofanhydrous pyridine were then added and stirring continued overnight. Thebulk of the solvent was evaporated in vacuo at 35°-40° C. and theconcentrate dissolved in 200 mL of methylene chloride. The methylenechloride solution was washed with 100 mL of water, dried over anhydrousmagnesium sulfate, filtered and concentrated in vacuo. The residue waspurified on a 1.5×50 cm silica gel column eluted @ 5 psi with 200 mL ofhexane, followed by 200 mL of 2% acetone in hexane, followed by 200 mLof 3% acetone in hexane, followed by 200 mL of 4% acetone in hexane andfinally 200 mL of 10% acetone in hexane, to give 583 mg (20% yield) ofthe title compound; MS DCI-NH₃ M/Z: 388 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ 0.04(s, 12H), 0.87 (s, 18H), 2.61 (d, 4H), 3.58 (s, 4H), 3.82 (s, 3H).

Step C:3.3-Bis(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutylamine

Following the procedures described in detail in Step G of Example 25,replacing the product of Step F of Example 25 with the product of Step Babove, the O-methyl oxime is reduced to the title compound.

Step D:2-Amino-4-hydroxy-5-nitro-6-(3',3'-bis(((1,1-dimethylethyl)dimethyl-silyl)oxymethyl)-cyclobutylamino)pyrimidine

Following the procedures described in Step H of Example 25, replacingthe product of Step G of Example 25 with the product of Step C above,the title compound is prepared.

Step E: 9-(3,3-Bis(hydroxymethyl)cyclobutyl)guanine

Following the procedures described in Step I of Example 25, replacingthe product of Step H of Example 25 with the product of Step D above,the title compound is prepared.

EXAMPLE 48 9-(3,3-Bis(hydroxymethyl)-cyclobutyl)adenine

Following the procedures in Example 4, replacing the product of Step Eof Example 1 with3,3-bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-cyclobutylamine,the product of Step C of Example 47, the title compound is prepared.

EXAMPLE 49 9-(3.3-Bis(hydroxymethyl)cyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with3,3-bis(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutylamine, theproduct of Step C of Example 47, the title compound is prepared.

EXAMPLE 50 9-(3,3-Bis(hydroxymethyl)-cyclobutyl)thymine

Following the procedures described in Example 2, replacing, in Step A,the product of Step D of Example 1 with3,3-bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylamine, theproduct of Step C of Example 47, and replacing, in Step B,(E)-3-ethoxyacryloyl chloride with 3-methoxymethacrylic acid chloride,the title compound is prepared.

EXAMPLE 51 9-(3,3-Bis(hydroxymethyl)-cyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 49, the titlecompound is prepared.

EXAMPLE 52 9-(3'-Hydroxycyclobutyl)adenine Step A:N-(Benzyloxycarbonyl)-3-amino-1-cyclobutanone

N-(Benzyloxycarbonyl)-3-methylenecyclobutanamine (4 g, 18.4 mmol) fromStep A of Example 5, 34 mL of methanol and 136 mL of methylene chloridewere mixed together and cooled to -78° C. under a nitrogen atmosphere.Ozone was bubbled through the mixture for approximately 20 minutes andthen the reaction mixture was flushed with nitrogen for approximately 10minutes. Dimethyl sulfide (17 mL) was added to the reaction mixture andthe reaction mixture was then stirred for 0.5 h at -78° C. and 0.5 h atambient temperature. The reaction mixture was concentrated under reducedpressure to a syrup. The syrup (6.2 g) was purified on a 1.5×40 cmsilica gel column, rinsed with hexane and eluted @ 5 psi with 400 mL of25% acetone in hexane to give 3.74 g (93% yield) of the title compound;MS DCI-NH₃ M/Z: 237 (M+NH₄)⁺ ; ¹ H NMR (CDCl.sub. 3) δ 3.10 (m, 2H),3.43 (m, 2H), 4.31 (m, 1H), 5.13 (s, 2H), 7.45 (s, 5H).

Step B: N-(Benzyloxycarbonyl)-3-amino-1-cyclobutanol

N-(Benzyloxycarbonyl)-3-amino-1-cyclobutanone (3.51 g, 16.0 mmol) fromStep A was dissolved in 100 mL of THF and the THF solution was cooled to-78° C. with stirring under a nitrogen atmosphere. To the solution wasadded 17.6 mL (17.6 mmol) of potassium tri-sec-butylborohydride (sold byAldrich Chemical Company as a 1M solution in THF under the registeredtrademark K-Selectride®) and stirring was continued for 10 minutes. Thereaction mixture was allowed to warm to 0° C. and then quenched with1.16 mL (1 equivalent) of glacial acetic acid. The reaction mixture wasthen filtered through Celite filter aid and concentrated in vacuo. Theresidue (3.1 g) was dissolved in ˜10 mL of methylene chloride andpurified on a 1.5×45 cm silica gel column eluted @ 5 psi with 250 mL ofacetone:hexane (1:2 v/v), followed by 200 mL of acetone:hexane (1:1 v/v)to give 2.22 g (63% yield) of the title compound; MS DCI-NH₃ M/Z: 222(M+H)⁺, 239 (M+NH₄)⁺ ; ¹ H NMR (CD₃ OD) δ 1.81 (m, 2H), 2.62 (m, 2H),3.60 (m, 1H), 3.90 (m, 1H), 5.09 (s, 2H), 7.25-7.40 (m, 5H).

Step C:3-(Benzyloxycarbonylamino)-1-(((1,1-dimethylethyl)dimethylsilyl)oxy)-cyclobutane

N-(Benzyloxycarbonyl)-3-amino-1-cyclobutanol (2.22 g, 10 mmol) from StepB and t-butyldimethylsilyl chloride (4.8 g, 32 mmol) were combined in 25mL of anhydrous pyridine and the cloudy suspension was stirred over theweekend at ambient temperature, under a nitrogen atmosphere. After 65 h,the solution was concentrated in vacuo at 35°-40° C. The concentrate wasdiluted with 250 mL of methylene chloride and the methylene chloridesolution was washed with 3×100 mL of water, dried over anhydrousmagnesium sulfate and concentrated in vacuo. The residue (3.9 g) waspurified on a 1.0×45 cm silica gel column eluted @ 5 psi with 100 mL ofhexane, followed by 200 mL of 10% acetone in hexane to give 3.16 g (88%yield) of the title compound; MS DCI-NH₃ M/Z: 336 (M+H)⁺, 353 (M+NH₄)⁺ ;¹ H NMR (CDCl₃) δ - 0.03 (s, 6H), 0.83 (s, 9H), 1.75 (m, 2H), 2.68 (m,2H), 3.69 (m, 1H), 3.93 (m, 1H), 5.06 (s, 2H), 7.30 (m, 5H).

Step D: 3-Amino-1-(1,1-dimethylethyl)dimethylsilyl)oxy)cyclobutane

3-(Benzyloxycarbonylamino)-1-(1,1-dimethylethyl)dimethylsilyl)oxy)-cyclobutane(3.16 g, 9.4 mmol) from Step C was dissolved in 75 mL of methanol and0.1 g of 10% palladium on carbon was added. The reaction mixture wasstirred under hydrogen at ambient temperature and atmospheric pressurefor 3 h. The catalyst was removed by filtration through a Millepore 0.45μm filter and the filtrate was concentrated under reduced pressure togive a quantitative yield of the title compound; MS DCI-NH₃ M/Z: 202(M+H)⁺, 219 (M+NH₄)⁺ ; ¹ H NMR (CDCl₃) δ -0.03 (s, 6H), 0.83 (s, 9H),1.60 (m, 2H), 2.60 (m, 2H), 2.85 (m, 1H), 3 33 (m, 1H).

Step E:5-Amino-4-chloro-6-(3'-(((1,1-dimethylethyl)dimethylsilyl)oxy)-1'-cyclobutylamino)pyrimidine

3-Amino-1-((1,1-dimethylethyl)dimethylsilyl)oxy)cyclobutane (1.9 g, 9.4mmol) from Step D, 5-amino-4,6-dichloropyrimidine (2.3 g, 14.1 mmol) andtriethylamine (6.57 mL (47 mmol) were combined in 100 mL of n-butanoland the reaction mixture was heated at reflux temperature under anitrogen atmosphere for 24 h. An additional 4 mL of triethylamine wasadded and reflux was continued for 5 h. The reaction mixture wasconcentrated in vacuo and the residue was eluted with 20% water inmethanol through a 1.5×33 cm column of strongly basic resin (60 mL)which had been packed with the same solvent. The eluate from the columnwas concentrated in vacuo. The residue (3.9 g) was dissolved in ˜25 mLof methylene chloride and purified on a 1.8×50 cm silica gel columneluted with 250 mL of methylene chloride, followed by 250 mL of 1%methanol in methylene chloride, followed by 250 mL of 2% methanol inmethylene chloride and finally 250 mL of 3% methanol in methylenechloride, to give 2.8 g (91% yield) of the title compound; MS DCI-NH₃M/Z: 329 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ -0.03 (m, 6H), 0.83 (m, 9H), 1.80(m, 2H), 2.80 (m, 2H), 3.30 (bs, 2H-NH₂), 4.02 (m, 1H), 8.0 (s, 1H).

Step F: 9-(3'-Hydroxy-1'-cyclobutyl)-6-chloropurine

5-Amino-4-chloro-6-(3'-(((1,1-dimethylethyl)dimethylsilyl)oxy)-1'-cyclobutyl-amino)pyrimidine(2.8 g, 8.5 mmol) from Step E and 75 mL of diethoxymethyl acetate werecombined under a nitrogen atmosphere and the mixture was heated atreflux temperature for approximately 22 h then concentrated to an oil.The oil was dissolved in 50 mL of toluene and 100 mg ofp-toluenesulfonic acid was added. The resultant solution was stirred atambient temperature for 1 h then concentrated in vacuo. The residue wasdissolved in 75 mL of methanol which had been saturated with ammonia at0° C. The solvents were evaporated and three 10 mL portions of methanolwere added to the residue and evaporated. The residue was then dissolvedin 75 mL of methanol and the pH of the solution was adjusted to ˜3 withp-toluenesulfonic acid. The solution was stirred at ambient temperaturefor approximately 1 h and then neutralized with methanol saturated withammonia and concentrated. The residue was dissolved in ˜1 mL ofmethylene chloride and purified on a 1.5×45 cm silica gel column eluted@ 5 psi with 200 mL of methylene chloride, followed by 200 mL of 5%methanol in methylene chloride and finally 10% methanol in methylenechloride to give 1.50 g (79% yield) of the title 7(compound; MS DCI-NH₃M/Z: 225 (M+H)⁺, 242 (M+NH₄)⁺ ; ¹ H NMR (CD₃ OD) δ 2.66 (m, 2H), 3.10(m, 2H), 4. 22 (m, 1H), 4.72 (m, 1H), 6.68 (s, 1H), 8.73 (s, 1H).

Step G: 9-(3'-Hydroxycyclobutyl)adenine

9-(3'-Hydroxy-1'-cyclobutyl)-6-chloropurine (0.8 g, 3.56 mmol) from StepF and 20 mL of condensed ammonia were combined with 10 mL of methanol ina tube. The tube was sealed and heated at 60° C. for 41 h then cooled to-78° C. and opened. The solution was evaporated to a solid residue whichwas triturated with 10 mL of methanol at 65° C. The mixture was cooledto 4° C. and the solvent removed by decantation. The solid was dried invacuo to give 654 mg (89% yield) of the title compound; MS DCI-NH₃ M/Z:206 (M+H)⁺ ; ¹ H NMR (CD₃ OD) δ 2.54 (m, 2H), 3.00 (m, 2H), 4.19 (m,1H), 4.60 (m, 1H), 8.20 (s, 1H), 8.24 (s, H).

EXAMPLE 53 9 -(3'-((Phosphonyl)methoxy)cyclobutyl)adenine ammonium saltStep A: 9-(3'((Diethylphosphonyl)methoxy)cyclobutyl)adenine

A mixture of 378 mg (1.84 mmol) of 9-(3'-hydroxycyclobutyl)adenine, theproduct of Example 52, in 100 mL of freshly distilled THF was cooled to0° C. and treated with 62 mg (2.6 mmol) of sodium hydride. After 10minutes, 718 mg (2.4 mmol) of diethyl phosphonomethyl triflate was addedand stirring was continued at 0° C. for 4.5 h under a nitrogenatmosphere. At this time an additional 200 μL of diethylphosphono-methyl triflate was added and the stirring was continuedagain. After 6 h, the reaction was quenched with methanol andconcentrated in vacuo. The residue was dissolved in 2 mL of methylenechloride and applied to a 1.0×45 cm silica gel column eluted @ 5 psiwith 100 mL of methylene chloride, followed by 100 mL of 3% methanol inmethylene chloride, followed by 100 mL of 5% methanol in methylenechloride and finally 100 mL of 10% methanol in methylene chloride, togive, after all of the fractions containing the desired product werecombined and concentrated,222 mg (34% yield) of the title compound; MSDCI-NH₃ M/Z: 356 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ 1.38 (t, 6H), 2.60 (m, 2H),3.07 (m, 2H), 3.79 (m, 2H), 4. 11 (m, 1H), 4.21 (m, 4H), 4.68 (m, 1H),7.97 (s, 1H), 8.35 (s, 1H).

Step B: 9-(3'-((Phosphonyl)methoxy)cyclobutyl)adenine ammonium salt

A mixture of 286 mg (0.806 mmol) of the diethyl ester from the previousstep was dissolved in 5 mL of acetonitrile and treated with 1.01 mL (8.1mmol) of bromotrimethylsilane at ambient temperature under a nitrogenatmosphere for 21 h. The reaction mixture was concentrated in vacuo,taken up in 5 mL of water and again concentrated. The residue wasdissolved in 1 mL of concentrated aqueous ammonium hydroxide solutionand the resultant solution was concentrated in vacuo. The residue wasdissolved in 2 mL of water and purified on a 1.5×45 cm reverse phasecolumn of Bondesil® C18 (40 μm particles) packed with methanol,equilibrated with water @ 10 psi and eluted with water @ 10 psi to give122 mg (45% yield) of the title compound as the ammonium salt; MSDCI-NH₃ M/Z: 300 (M+H)⁺ free acid; ¹ H NMR (D₂ O) δ 2.52 (m, 2H), 3.06(m, 2H), 3.64 (d, 2H), 4.17 (m, 1H), 4.55 (m, 1H), 8.13 (s, 1H), 8.27(s, 1H).

EXAMPLE 54 9-(3'-Hydroxycyclobutyl)guanine

Following the procedures described in Steps O and P of Example 42,replacing the product of Step N of Example 42 with3-amino-1-(1,1-dimethylethyl)dimethylsilyl)oxy)cyclobutane, the productof Step D of Example 52, the title compound is prepared.

EXAMPLE 55 9-(3'-Hydroxycyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with3-amino-1-(1,1-dimethylethyl)dimethylsilyl)oxy-cyclobutane, the productof Step D of Example 52, the title compound is prepared.

EXAMPLE 56 9-(3'-Hydroxycyclobutyl)thymine

Following the procedures described in Example 2, replacing, in Step A,the product of Step D of Example 1 with3-amino-1-(1,1-dimethylethyl)dimethylsilyl)oxycyclobutane, the productof Step F of Example 55, and replacing, in Step B, (E)-3-ethoxyacryloylchloride with 3-methoxymethacryloyl chloride, the title compound isprepared.

EXAMPLE 57 9-(3'-Hydroxycyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 55, the titlecompound is prepared.

EXAMPLE 58 9-(3'-Hydroxy-2'-hydroxymethyl-1'-cyclobutyl)cyanine Step A:2-Amino-6-chloro-9-(3',3'-diethoxy-2'-methoxycarbonyl-1'-cyclobutyl)purine

Methyl 4,4-diethoxy-1-cyclobutenecarboxylate (2.3 g, 11.5 mmol),prepared as described by M. F. Semmelhack, et al. in J Am Chem Soc. 104,747-759 (1982), was dissolved in 50 mL of DMF and 1.95 g (11.5 mmol) of2-amino-6-chloropurine was added, followed by 50 μL of1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The solution was stirred atambient temperature for 1 h and 0.5 mL of DBU was added and stirringcontinued for 0.5 h. The reaction mixture was stirred for an additional2 h and then stored in the refrigerator overnight. The reaction mixturewas then concentrated and the residue purified on a silica gel columneluted with 2% methanol in methylene chloride to give 2.9 g (70% yield)of the title compound; MS DCI-NH₃ M/Z: 371 (M+H)⁺, 388 (M+NH₄)⁺.

Step B: 2-Amino-6-chloro-9-(3',3'-diethoxy-2'-hydroxymethyl-1'-cyclobutyl)-purine

2-Amino-6-chloro-9-(3',3'-diethoxy-2'-methoxycarbonyl-1'-cyclobutyl)purine(1.9 g, 5.1 mmol) from Step A was dissolved in 70 mL of THF and cooledto 0° C. in an ice water bath. Lithium aluminum hydride (280 mg, 1.5equivalents) was added to the solution in small batches over a 30 minperiod. The reaction mixture was stirred at 0° C. for 1.5 h and then thereaction was quenched by the addition of 0.4 mL of water, followed by0.4 mL of 15% aqueous sodium hydroxide solution and 1.2 mL of water. Thereaction mixture was then stirred vigorously for 20 min at ambienttemperature. The aluminum salts were filtered through Celite filter aidand the filtrate was concentrated under reduced pressure to give 1.67 gof the title compound as a white solid; MS DCI-NH₃ M/Z: 343 (M+H)⁺, 360(M+NH₄)⁺.

Step C:2-Amino-6-chloro-9-((3'-oxo-2'-hydroxymethyl)-1'-cyclobutyl)purine

2-Amino-6chloro-9-(3',3'-diethoxy-2'-hydroxymethyl-1'-cyclobutyl)purine(1.3 g) from Step B and acetone (70 mL) and 10 mL of 1N hydrochloricacid solution were combined and stirred at ambient temperature for 4 h.At this time 5 mL of 1M hydrochloric acid was added and stirringcontinued overnight. After 18 h another 5 mL portion of 1N hydrochloricacid solution was added. The reaction mixture was then neutralized with1N sodium hydroxide solution and extracted with 3×200 mL of ethylacetate. The ethyl acetate solution was concentrated and the residue waspurified on a silica gel column eluted with 10% methanol in methylenechloride to give 470 mg of the title compound; MS DCI-NH₃ M/Z: 269(M+H)⁺, 286 (M+NH₄)⁺.

Step D:2-Amino-6-chloro-9-(3'-hydroxy-2'-hydroxymethyl-1'-cyclobutyl)-purine

2-Amino-6-chloro-9-(3'-oxo-2'-hydroxymethyl-1'-cyclobutyl)purine (430mg) from Step C was dissolved in 45 mL of methanol and the resultantsolution was cooled to 0° C. Sodium borohydride was added to thesolution portionwise and the reaction mixture was stirred for 15 min at0° C. The reaction was then quenched by the addition of acetone. Thereaction mixture was concentrated and the residue was purified on asilica gel column eluted with 10% methanol in methylene chloride to give370 mg of the title compound; MS DCI-NH₃ M/Z: 270 (M+H)⁺, 287 (M+NH₄)⁺.

Step E: 9-((3'-Hydroxy-2'-hydroxymethyl)-1'-cyclobutyl)guanine

2-Amino-4-chloro-9-((3'-hydroxy-2'-hydroxymethyl-1'-cyclobutyl)purine(78 mg) from Step D and 5 mL of 1N hydrochloric acid were combined andheated at 105° C. for 2.5 h. The reaction mixture was concentrated invacuo to give 62 mg of the title compound; MS DCI-NH₃ M/Z: 252 (M+H)⁺,269 (M+NH₄)⁺ ; ¹ H NMR (d6-DMSO) δ 2.40 (m, 1H), 2.62-2.80 (m, 2H), 3.55(m, 2H), 3.78 (m, 1H), 4.12 (m, 1H), 4.66 (t, 1H, J=5.5 Hz), 5.22 (d,1H, J=7.0 Hz), 6.40 (bs, 2H), 7.82 (s, 1H), 10.50 (bs, 1H).

EXAMPLE 599-(2'-(Hydroxymethyl)-3'-((phosphonyl)methoxy)-1'-cyclobutyl)guanineStep A:2-Amino-6-chloro-9-(3'-hydroxy-2'-(((1,1-dimethylethyl)dimethyl)dimethylsilyloxy)methyl)-1'-cyclobutyl)purine

2-Amino-6-chloro-9-(3'-hydroxy-2'-hydroxymethyl-1'-cyclobutyl)purine(390 mg, 1.45 mmol), the product of Step D of Example 58 was dissolvedin 10 mL of DMF and the solution was cooled to 0° C.t-Butyldimethylsilyl chloride (240 mg, 1.1 equivalents) and imidazole(200 mg, 1.1 equivalents) were added sequentially and the reactionmixture was stirred at 0° C. for 1.25 h. The reaction mixture wasconcentrated and the residue was chromatographed on a silica gel columneluted with 5% methanol in methylene chloride to give 140 mg of thetitle compound; ¹ H NMR (d6-DMSO) δ ˜0.04 (s, 6H), 0.73 (s, 9H), 2.19(m, 1H), 70 (m, 1H), 2.90 (m, 1H), 3.70 (m, 1H), 3.78 (m, 2H), 4.20 (m,1H), 32 (d, 1H-OH), 6.81 (bs, 2H-NH₂), 8.29 (s, 1H); MS DCI-NH₃ M/Z: 384(M+H)⁺, 401 (M+NH₄)⁺.

Step B:2-Amino-6-chloro-9-(3'-((diethylphosphonyl)methoxy)-2'-(((1,1-dimethylethyl)dimethylsilyloxy)methyl)-1'-cyclobutyl)-purine

A suspension of sodium hydride (18.5 mg) in 10 mL THF was cooled to 0°C. and 155 mg (0.42 mmol) of2-amino-6-chloro-9-(3'-hydroxy-2'-(((1,1-dimethylethyl)dimethylsilyloxymethyl)-1'-cyclobutyl)purinefrom Step A was added, followed after 10 minutes by 108 μL of diethylphosphonomethyl triflate. After stirring the reaction mixture for 1 h,the reaction was quenched by the addition of methanol and the reactionmixture was concentrated under reduced pressure. The residue waspurified on a silica gel column eluted with 2% methanol in methylenechloride to give 170 mg (80% yield) of the title compound; ¹ H NMR(d6-DMSO) δ ˜0.02 (2s, 6H), 0.77 (s, 9H), 2.38 (m, 1H), 2.75 (m, 1H),3.07 (m, 1H), 3.76 (d, 2H), 3.78-3.92 (m, 3H), 4.35 (m, 1H), 6.88 (bs,2H-NH2), 8.31 (s, 1H); MS DCI-NH₃ M/Z: 534 (M+H)⁺, 551 (M+NH₄)⁺.

Step C:2-Amino-6-bromo-9-(3'-((diethylphosphonyl)methoxy)-2'-hydroxymethyl)-1'-cyclobutyl)purine

2-Amino-6-chloro-9-(3'-((diethylphosphonyl)methoxy-2'-((1,1-dimethylethyl)-dimethylsilyloxy)methyl)-1'cyclobutyl)purine(169 mg, 0.32 mmol) from Step B was dissolved in 2 mL of acetonitrileand 420 mL of trimethylsilyl bromide was added. The faintly yellowsolution was stirred at ambient temperature under an argon atmospherefor 16 h and then concentrated. The residue was dried and suspended in 2mL of water. The water was removed in vacuo and this step was repeated.The residue was dissolved in methanol and reconcentrated then dissolvedin THF and reconcentrated to give 170 mg of the title compound as aglassy pale yellow solid which was taken on to the next step withoutpurification; FAB⁻ MS: 408; FAB⁺ MS: 410.

Step D:9-((2'-Hydroxymethyl)-3'-((phosphonyl)methoxy)-1'-cyclobutyl)guanine

2-Amino-6-bromo-9-((3'-(phosphonyl)methoxy)-2'-hydroxymethyl)-1'-cyclobutyl)purine(170 mg) from Step C and 7 mL of 1 N hydrochloric acid were combined andheated at 90° C. for 2 h and 10 min. The reaction mixture was thenallowed to cool to ambient temperature and was concentrated to drynesson the rotovap. The residue was reconstituted with water and evaporatedto dryness twice then dissolved in 0.5 mL of concentrated aqueousammonium hydroxide solution and again concentrated to dryness. Theresidue was purified on a reverse phase C-18 column eluted with water togive 101 mg of the title compound; MS FAB M/Z 346 (M+H)⁺ ; ¹ H NMR (D₂O) δ 2.44 (m, 1H), 2.96 (m, 1H), 3.04 (m, 1H), 3.67 (d, 1H), 3.82 (d,1H), 3.98 (m, 1H), 4.31 (m, 1H), 8.01 (s, 1H).

EXAMPLE 60 9-(3'-Hydroxy-2'-(hydroxymethyl)-1'-cyclobutyl)adenine

Following the procedures described in Steps A-D of Example 58, replacing2-amino-6-chloropurine in Step A with adenine, the title compound wasprepared; FAB MS M/Z: 236 (M+H)⁺ ; ¹ H NMR (d6-DMSO) δ 2.32 (m, 1H),2.72 (m, 1H), 2.84 (m, 1H), 3.56 (m, 2H), 3.82 (m, 1H), 4.30 (q, 1H),4.79 (t, 1H), 5.31 (d, 1H), 8.12 (s, 1H), 8.24 (s, 1H).

EXAMPLE 619-(2'-(Hydroxymethyl)-3'-((phosphonyl)methoxy)-1'-cyclobutyl)adenine

Following the procedures described in Steps A-C of Example 59, replacing2-amino-6-chloro-9-(3'-hydroxy-2'-hydroxymethyl-1'-cyclobutyl)purine inStep A with the product of Example 60, the title compound is prepared.

EXAMPLE 62 9-(2'-(2"-(Hydroxy)ethyl)-3'-(hydroxymethyl)-1'-cyclobutyl)guanine Step A:2-(2-(Hydroxy)ethyl)-3-(hydroxymethyl)cyclobutanol

2-Oxa-3-oxo-6-formyl-bicyclo[3.2.0]heptane (950 mg, 6.78 mmol), preparedas described by A. E. Greene, et al. in Tetrahedron Letters, 3755-8(1976), was dissolved in 8 mL of anhydrous THF and the resultantsolution was cooled to 0° C. After stirring the solution at 0° C. for0.5 h, 27.2 mL (27.1 mmol) of diborane (1M solution in THF) was addedand stirring was continued for another 0.5 h. The reaction was carefullyquenched with methanol, concentrated in vacuo and dried in vacuo to give800 mg (81% yield) of the title compound which was taken on to the nextstep without purification; MS DCI-NH₃ M/Z: 147 (M+H)⁺, 164 (M+NH₄)⁺.

Step B:2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutanol

2-(2-(Hydroxy)ethyl)-3-(hydroxymethyl)cyclobutanol (800 mg, 5.48 mmol)from Step A was mixed with 1.726 g (11.4 mmol) of t-butyldimethylsilylchloride and 1.57 g (23 mmol) of imidazole in 18 mL of DMF:methylenechloride (1:8 v/V) and the reaction mixture was stirred at ambienttemperature for 2 h under a nitrogen atmosphere. The reaction mixturewas concentrated in vacuo and the residue dissolved in ethyl acetate.The ethyl acetate solution was washed with brine, dried over anhydroussodium sulfate, filtered and concentrated. The residue was purified on asilica gel column eluted with 10% ethyl acetate in hexane to give 900 mg(44% yield) of the title compound; MS DCI-NH₃ M/Z: 375 (M+H)⁺, 392(M+NH₄)⁺.

Step C: 2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((11-dimethylethyl)dimethylsilyl)oxymethyl)-1-O-methanesulfonylcyclobutanol

2-(2-((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethyl-silyl)oxymethyl)cyclobutanol(160 mg, 0.43 mmol) from Step B was dissolved in 2 mL of methylenechloride and the resultant solution was cooled to 0° C. Triethylamine(120μL) was added, followed by 36 μL of methanesulfonyl chloride. Afterstirring the reaction mixture for 30 min at 0° C., it was concentratedin vacuo and the residue was purified on a silica gel column eluted with10% ethyl acetate in hexane to give 180 mg (89% yield) of the titlecompound.; MS DCI-NH₃ M/Z: 447 (M+H)⁺, 464 (M+NH₄)⁺.

Step D:2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-azidocyclobutane

2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl-3-(((1,1-dimethylethyl)dimethyl-silyl)oxymethyl)-1-O-methanesulfonylcyclobutanol(180 mg, 0.41 mmol) was mixed with 200 mg (4.1 mmol) of lithium azide in4 mL of DMF. The reaction mixture was heated at 80° C. for 2 h thenconcentrated in vacuo. The residue was purified on a silica gel columneluted with 5% ethyl acetate in hexane to give 120 mg (73% yield) of thetitle compound; MS DCI-NH₃ M/Z: 400 (M+H)⁺, 417 (M+NH₄)⁺.

Step E:2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-aminocyclobutane

2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethyl-silyl)oxymethyl)-1-azidocyclobutane(980 mg, 2.45 mmol), prepared as described in Step D above, wasdissolved in 20 mL of methanol and an excess of palladium on carbon wasadded to the solution under a nitrogen atmosphere. The reaction mixturewas stirred at ambient temperature and atmospheric pressure underhydrogen for 0.5 h. The catalyst was removed by filtration and washedwith 10 mL of methanol. The filtrate was concentrated in vacuo to give850 mg (93%) yield of the title compound; MS DCI-NH₃ M/Z: 374 (M+H)⁺,391 (M+NH4)+.

Step F:2-Amino-6-(2'-(2-(((1,1-dimethylethyl)dimethylsilyl)oxy)ethyl)-3'-((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1'-cyclobutylamino)-4-hydroxy-5-nitropyrimidine

2-(2-(((1,1-Dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)-dimethylsilyl)oxymethyl)-1-aminocyclobutane(820 mg, 2.2 mmol), from Step E,6-chloro-2-amino-4-hydroxy-5-nitropyrimidine (450 mg, 2.35 mmol) andtriethylamine (460 μL, 3.3 mmol) were mixed together in 25 mL of DMF andthe reaction mixture was heated at 60° C. for 1 h. The reaction mixturewas concentrated in vacuo and the residue was extracted with 3×100 mL ofethyl acetate. The ethyl acetate solution was washed with brine, driedover anhydrous sodium sulfate, filtered and concentrated. The residuewas purified on a silica gel column eluted with 5% methanol in methylenechloride to give 860 mg (74% yield) of the title compound; MS DCI-NH₃M/Z: 528 (M+H)⁺, 445 (M+NH₄)⁺.

Step G:9-(2'-(2-(Hydroxy)ethyl)-3'-(hydroxymethyl)-1'-cyclobutyl)guanine

Following the procedures described in Step P of Example 42, replacing470 mg (0.63 mmol) of2-amino-4-hydroxy-5-nitro-6-(2'-(((1,1-dimethylethyl)diphenylsilyl)oxy)-3'-(((1,1-dimethylethyl)diphenylsilyl)oxymethyl)cyclobutylamino-pyrimidinewith 460 mg (0.872 mmol) of2-amino-6-(2'-(2-(((1,1-dimethylethyl)dimethylsilyl)oxy)ethyl)-3'-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1'-cyclobutylamino)-4-hydroxy-5-nitropyrimidine, from Step F, and heatingthe formic acid solution at 160° C. for 2.5 h, instead of at 130° C. for3 h, the title compound was prepared (60 mg) in a 22% yield; MS DCI-NH₃M/Z: 280 (M+H)⁺ ; ¹ H NMR (d6-DMSO) δ 1.65 (m, 1H), 1.89 (m, 1H), 2.04(q, 1H), 2.37 (m, 1H), 2.55 (m, 1H), 3.28 (m, 2H), 3.52 (m, 2H), 4.26(q, 1H), 4.37 (t, 1H-OH), 4.63 (t, 1H-OH), 6.39 (bs, 2H-NH2), 7.87 (s,1H).

EXAMPLE 639-(2'-(2-Hydroxy)ethyl)-3'-hydroxymethyl-1'-cyclobutyl)adenine

Following the procedures in Example 4, replacing the product of Step Eof Example 1 with2-(2-(((1,1-dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-aminocyclobutane,the product of Step E of Example 62, the title compound is prepared withthe hydroxyl groups protected with the t-butyldimethylsilyl group. Theprotecting groups are removed as described in Step E of Example 1.

EXAMPLE 649-(2'-(2-(Hydroxy)ethyl)-3'-hydroxymethyl-1'-cyclobutyl)uracil

Following the procedures described in Example 2, replacing the productof Step D of Example 1 with2-(2-(((1,1-dimethylethyl)dimethylsilyl)oxy)ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-aminocyclobutane,the product of Step E of Example 62, the title compound is prepared.

EXAMPLE 65

9-(2'(2-(Hydroxyl)ethyl)-3'-hydroxymethyl-1'-cyclobutyl)thymine

Following the procedures described in Example 2, replacing, in Step A,the product of Step D of Example 1 with2-(2-(((1,1-dimethylethyl)dimethylsilyl)oxy)-ethyl)-3-(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)-1-aminocyclobutane,the product of Step E of Example 62, and replacing, in Step B,(E)-3-ethoxyacryloyl chloride with 3-methoxymethacryloyl chloride, thetitle compound is prepared.

EXAMPLE 669-(2'-(2-(Hydroxy)ethyl)-3'-hydroxymethyl-1'-cyclobutyl)cytosine

Following the procedures described in Example 3, replacing the productof Step B of Example 2 with the product of Example 64, the titlecompound is prepared.

EXAMPLE 67 4-Amino-9-bromo-7-(2',3'-bis(hydroxymethyl)cyclobutyl)-7H-pyrrolo[2.3-d]pyrimidine Step A:3-((4'-Chloro-5'-(2.2-diethoxyethyl)-6'-pyrimidiyl)amino)-1,2-bis(hydroxymethyl)cyclobutane

2,3-Bis(hydroxymethyl)cyclobutylamine hydrochloride was generated by theprocedures described in Step E of Example 1 from 4.32 g (12 mmol) of2,3-bis(((1,1-dimethylethyl)dimethylsilyl)oxymethyl)cyclobutylamine, theproduct of Step D of Example 1 and added to a solution of 6.336 g (24mmol) of 4,6-dichloro-5-(2,2-diethoxyethyl)pyrimidine, prepared asdescribed by J. A. Montgomery and K. Hewson in J Medicinal Chemistry,10, 665-7 (1967), in 30 mL of ethanol. Triethylamine (3.3 mL, 24 mmol)was added and the reaction mixture was heated at reflux for 7 h. Anadditional 1.5 mL of triethylamine was added and reflux continued for0.5 h. The temperature was allowed to fall below reflux temperature andthe solution was concentrated in vacuo to a solid residue. The residuewas dissolved in methylene chloride and the methylene chloride solutionwas washed with aqueous sodium bicarbonate solution and brine, driedover anhydrous magnesium sulfate, filtered and concentrated. The residuewas purified on a 2.8×73 cm silica gel column eluted with 5% methanol inmethylene chloride followed by 10% methanol in methylene chloride togive 2.88 g (67% yield) of the title compound; MS DCI-NH₃ M/Z: 360(M+H)⁺.

Step B:4-Chloro-7-(2',3'-bis(hydroxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine

3-((4'-Chloro-5'-(2,2-diethoxyethyl)-6'-pyrimidinyl)amino)-1,2-bis(hydroxymethyl)cyclobutane(2.88 g, 8 mmol) from Step A was dissolved in 43 mL of dioxane and 10.8mL of 1 N hydrochloric acid solution was added. The resultant solutionwas stirred at ambient temperature for 2 days and then 1.5 mL ofconcentrated aqueous ammonium hydroxide solution was added. The solutionwas concentrated in vacuo and ethanol added to the residue. The ethanolwas evaporated and the residue was treated with 300 mL of warmchloroform. The chloroform solution was filtered and the filtrate waswashed with water (pH of water wash was˜4), sodium bicarbonate andbrine, dried over anhydrous magnesium sulfate, filtered and concentratedin vacuo to give 1.75 g (82% yield) of the title compound; MS DCI-NH₃M/Z: 268 (M+H)⁺ ; ¹ H NMR (CDCl₃) δ2.24 (m, 2H), 2.35 (m, 2H), 2.59-2.80(m, 4H), 3.60-3.90 (m, 4H), 4.81 (q, 1H), 6.64 (d, 1H), 7.40 (d, 1H),8.62 (s, 1H).

This product was carried on to the next step without purification.

Step C:9-Bromo-4-chloro-7-(2',3'-bis(hydroxymethyllcyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine

4-Chloro-7-(2',3'-bis(hydroxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine(26 mg, 0.1 mmol) from Step B was treated with 26.7 mg (0.15 mmol) ofN-bromosuccinimide (NBS) in 2.5 mL of chloroform, overnight at ambienttemperature. An additional 28 mg of NBS and 2 mL of chloroform were thenadded and stirring was continued overnight. The mixture was partitionedbetween water and chloroform and the chloroform solution was washed withaqueous thiosulfate solution, dried over anhydrous magnesium sulfate,filtered and concentrated. The residue was purified on a 2.0×12 cmsilica gel column eluted with 5% methanol in methylene chloride to give8.4 mg (24% yield) of the title compound; MS DCI-NH₃ M/Z: 346 (M+H)⁺,348 (MH+2)⁺ ; ¹ H NMR CD₃ OD) δ2.20-2.33 (m, 2H), 2.50-2.60 (m, 1H),2.75-2.85 (m, 1H), 3.65-3.71 (m, 4H), 5.03 (q, 1H), 7.93 (s, 1H), 8.57(s, 1H).

Step D:4-Chloro-7-(2',3'-bis(acetoxymethyl)cyclobutyl)-7H-pyrrolo[2.3-d]pyrimidine

4-Chloro-7-(2',3'-bis(hydroxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine(0.661 g (2.48 mmol) from Step B was treated with 0.612 g (567 μL, 6mmol) of acetic anhydride in 5 mL of methylene chloride and 2 mL ofpyridine at ambient temperature overnight. An additional 225 μL ofacetic anhydride and 2 m L of pyridine were then added and stirringcontinued at ambient temperature. After 4 h, the solution wasconcentrated in vacuo and complete removal of solvents was achieved byazeotropic distillation in vacuo with toluene. The residue was purifiedon a 2×30 cm silica gel column eluted with 50% ethyl acetate in hexaneto give 0.772 g (89% yield) of the title compound; MS DCI-NH₃ M/Z: 352(M+H)⁺ ; ¹ H NMR (CDCl₃) δ1.98 (s, 3H), 2.13 (s, 3H), 2.39 (m, 2H), 2.64(m, 1H), 3.02 (m, 1H), 4.10-4.30 (m, 4H), 4.95 (q, 1H), 6.63 (d, 1H),7.35 (d, 1H), 8.61 (s, 1H).

Step E:9-Bromo-4-chloro-7-(2',3'-bis(acetoxymethyl)cyclobutyl)-7H-pyrrolo[2.3-d]pyrimidine

4-Chloro-7-(2',3'-bis(acetoxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine(0.77 g, 2.19 mmol) from Step D was dissolved in 20 mL of methylenechloride and 0.303 g (2.19 mmol) of N-bromoacetamide (commerciallyavailable from Sigma Chemical Company) was added. The resultant solutionwas stirred for 2.5 h and then diluted with methylene chloride, washedwith aqueous sodium thiosulfate solution and saturated aqueous sodiumbicarbonate solution, dried over anhydrous magnesium sulfate, filteredand concentrated under reduced pressure. The residue was purified on a2×31 cm silica gel column eluted with 40% ethyl acetate in hexane togive 0.78 g (83% yield) of the title compound; MS DCI-NH₃ M/Z: 430(M+H)⁺ ; ¹ H NMR (CDCl₃) δ2.00 (s, 3H), 2.13 (s, 3H), 2.30-2.45 (m, 2H),2.65 (m, 1H), 2.97 (m, 1H), 4.15-4.30 (m, 4H), 4.96 (q, 1H), 7.41 (s,1H), 8. 61 (s, 1H).

Step F:4-Amino-9-bromo-7-(2',3'-bis(hydroxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine

9-Bromo-4-chloro-7-(2',3'-bis(acetoxymethyl)cyclobutyl)-7H-pyrrolo[2,3-d]pyrimidine(0.78 g, 1.82 mmol) from Step E was treated with a solution of 10 mL ofammonia in 20 mL of methanol for 6 h at 120° C in a sealed tube. Thesolvent was then evaporated and the residue crystallized from methanolto give 424 mg (71% yield) of the title compound; m.p. 185°-187° C.; MSDCI-NH₃ M/Z: 327 (M+H)⁺ ; (d6-DMSO) δ2.05 (m, 2H), 2.40 (m, 1H), 2.65(m, 1H), 3.40-3.52 (m, 4H), 4.61 (t, 1H --OH), 4.67 (t, 1H --OH), 4.80(q, 1H), 6.72 (bs, 2H --NH₂), 7.60 (s, 1H), 8.09 (s, 1H).

EXAMPLE 68

9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

Step A: Dimethyl 3-(phenylthio)cyclobutane-1,2-dicarboxylate

To a solution of 1.06 g (7.34 mmol) of dimethyl fumarate in 20 mL of dry1,2-dichloroethane under nitrogen atmosphere, was added with stirring,7.34 mmol of a 1.0 M solution of ethylaluminum dichloride in hexane. Theresultant yellow solution was heated to reflux and a solution of 1.0 g(7.34 mmol) of phenyl vinyl sulfide in 4 mL of dry 1,2-dichloroethanewas added dropwise, via syringe, over a period of 20 minutes. Thereaction mixture was allowed to stir at reflux for 3 h. After cooling toambient temperature, the reaction was quenched carefully with 100 mL of1.0 N hydrochloric acid solution and the reaction mixture was extractedwith 3×50 mL of ethyl acetate. The organic extract was washed with 2×50mL of water and 50 mL of brine, dried over anhydrous magnesium sulfate,filtered and concentrated to a viscous orange oil. The oil (1.56 g) waschromatographed on silica gel (25 g) eluted with 300 mL of 3% ethylacetate in 1,2-dichloroethane. The resultant yellow oil was purified bybulb-to-bulb distillation to give the title compound as a yellow oil;b.p 120° C. (0.05 mm Hg); EI-MS, m/e (relative intensity): 280 (M⁺, 18),136 (100), 91 (13); ¹ H NMR (CDCl₃) δ2.20 (q, 1H), 2.61 (m, 1H), 3.22(q, 1H), 3.34 (t, 1H), 3.66 (s, 3H), 3.67 (s, 3H), 3.87 (m, 1H), 7.30(m, 5H).

Step B: 2,3-Dicarbomethoxycyclobutyl phenyl sulfone

To a vigorously stirred solution of 1.05 g (3.75 mmol) of dimethyl3-(phenylthio)cyclobutane-1,2-dicarboxylate from Step A in 20 mL ofmethanol, was added slowly a suspension of 3.46 g (11.25 mmol) of OXONE(a commercially available mixture of sulfuric acid potassium salt andpotassium hydrogen peroxymonosulfate) in 20 mL of water. The resultantcloudy suspension was stirred for 0.5 h then diluted with 50 mL of waterand 100 mL of 1,2=dichloroethane. The phases were allowed to separateand the aqueous phase was extracted with 20 mL of 1,2-dichloroethane.The combined organic layers were washed with 2×50 mL of dilute aqueoussodium bicarbonate solution, 2×50 mL of water and 50 mL of brine, driedover anhydrous magnesium sulfate and concentrated to give 1.10 g (94%yield) of the title compound as a viscous oil; EI-MS, m/e (relativeintensity): 281 (M⁺ --OCH₃, 9), 171 (100), 139 (24), 111 (47); ¹ H NMR(CDCl₃) δ2.48 (m, 1H), 2.76 (m, 1H), 3.23 (q, 1H), 3.52 (s, 3H), 3.74(s, 3H), 3.80 (m, 1H), 3.92 (q, 1H), 7.58 (m, 2H), 7.68 (m, 1H), 7.89(m, 2H).

Step C:3-(2'-Amino-6'-chloro-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane

2-Amino-6-chloropurine (905 mg, 1.0 equiv) was dissolved in 40 mL ofanhydrous N,N-dimethylformamide (DMF) with heating. To the resultantsolution at ambient temperature under nitrogen atmosphere, was added asolution of 1.83 g (5.87 mmol) of 2,3-dicarbomethoxycyclobutyl phenylsulfone from Step B in 40 mL of dry DMF. To this soluion was added 1.76mL (2.0 equiv) of 1,8-diazabicycloundec-7-ene (DBU) and the resultingmixture was stirred for 18 h at 70° C. The reaction mixture was dilutedwith 250 mL of ethyl acetate, washed with 3×75 mL of saturated aqueousammonium chloride solution, 3×75 mL of water and 75 mL of brine, driedover anhydrous sodium sulfate, filtered and concentrated in vacuo togive 1.72 g (86% yield) of the title compound; MS DCI-NH₃ M/Z (relativeintensity): 342 (M⁺, 31), 340 (M+, 100); ¹ H NMR (CDCl₃) δminor isomer:2.5-3.6 (m, 3H), 3.69 (s, 3H), 3.78 (s, 3H), 4.46 (t, 1H), 4.94 (q, 1H),7.80 (s, 1H); major isomer: 2.5-3.6 (m, 3H), 3.12 (s, 3H), 3.80 (s, 3H),4.18 (t, 1H), 5.38 (q, 1H), 7.88 (s, 1H). This compound was taken on tothe next step without purification.

Step D:3-(2'-Amino-6'-methoxy-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane

Sodium methoxide (125 mL of a 0.65 M solution in anhydrous methanol) wasadded via syringe, under strictly anhydrous conditions, to 1.32 g (3.884mmol) of3-(2'-amino-6'-chloro-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane,from Step C, contained under nitrogen atmosphere in a vacuum dried flaskequipped with a magnetic stirrer and rubber septum. The resultant slurryhomogenized slowly over the 16 h reaction time. After 16 h of stirringat ambient temperature, the solution was treated with 25 mL of a 8.30 Msolution of anhydrous hydrogen chloride in methanol, affording a whiteprecipitate of sodium chloride. This mixture was stirred at ambienttemperature for 2 h and then the reaction was quenched by pouring themixture into 150 mL of saturated aqueous sodium bicarbonate solution.The methanol was removed on the rotory evaporator to give an oilyaqueous mixture which was extracted with 3×100 mL of ethyl acetate. Thecombined organic layers were washed with 50 mL of brine, dried overanhydrous magnesium sulfate, filtered and concentrated to give 1.21 g(93% yield) of the title compound as a tan oil that slowly crystallized;m.p. 143° C.; ¹ H NMR (CDCl₃) δ2.73-2.83 (m, 1H), 2.90-3.00 (m, 1H),3.18-3.25 (m, 1H), 3.71 (s, 3H), 3.79 (s, 3H), 4.07 (s, 3H), 4.11-4.19(m, 1H), 4.84 (bs, 2H), 4.87-4.96 (m, 1H), 7.70 (s, 1H). The product wastaken on to the next step without purification.

Step E:3-(2'-Amino-6'-methoxy-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane

3-(2'-Amino-6'-methoxy-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane(0.9 g, 2.68 mmol) from Step D was dissolved in 50 mL of anhydrous THFunder a nitrogen atmosphere. To this stirred solution at ambienttemperature was added lithium aluminum hydride (8.5 mL of a 1.0 Msolution in THF, 8.05 mmol) affording a white precipitate. This mixturewas stirred at ambient temperature for 1.0 h and then the reaction wasquenched by the successive dropwise addition of 0.3 mL of water, 0.3 mLof 15% aqueous sodium hydroxide solution and 0.9 mL of water. Themixture was filtered and the filter cake was washed with 50 mL of THF.The combined organic filtrates were dried over anhydrous magnesiumsulfate, filtered and concentrated to give 0.735 g (99% yield) of thetitle compound as a slightly yellowish colored oil. ¹ H NMR CD₃ OD)δ2.13-2.25 (m, 1H), 2.29-2.39 (m, 1H), 2.48-2.60 (m, 1H), 2.73-2.86 (m,1H), 3.66-3.72 (m, 4H), 4.04 (s, 3H), 4.51-4.61 (m, 1H), 4.88 (s,exchangable protons), 7.96 (s, 1H). The product was taken on to the nextstep without purification.

Step F: 9-(2',3'-Bis(hydroxymethyl)cyclobutyl)guanine

3-(2'-Amino-6'-methoxy-9'H-purin-9'-yl)-1,2-bis(hydroxymethyl)cyclobutane(0.711 g, 2.55 mmol) from Step E was dissolved in 50 mL of 1 N aqueoushydrochloric acid solution and the resultant solution was heated atreflux for 16 h, cooled to ambient temperature and concentrated underreduced pressure. The residue was re-dissolved in a small quantity ofwater and the pH of this solution was adjusted to 5.5 with 15% aqueoussodium hydroxide solution, affording a white precipitate. This materialwas recrystallized from 5 mL of water to give 473 mg (70% yield) of thetitle compound as a white powder; the ¹ H NMR spectrum of the productwas identical to a ¹ H NMR spectrum of the product of Example 1.

EXAMPLE 69

9-(2',3'-Bis(hydroxymethyl)cyclobutyl)adenine

Step A: 3-(6'-Amino-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane

To a mixture of 2,3-dicarbomethoxycyclobutyl phenyl sulfone (1.74 g,5.58 mmol), the product of Step B of Example 68, and 0.753 g (5.58 mmol)of adenine, was added 70 mL of anhydrous DMF. To the resultingsuspension was added 1.67 mL (2.0 equiv) of DBU and the resultantreaction mixture was stirred for 9 h at 75° C. The reaction mixture wasthen diluted with 250 mL of ethyl acetate, washed with 3×75 mL ofhalf-saturated aqueous ammonium chloride, 2×75 mL of water and 75 mL ofbrine. The organic phase was dried over anhydrous sodium sulfate,filtered and concentrated in vacuo to give 0.651 g (38% yield) of thetitle compound. MS DCI-NH3 M/Z: 306 (M+H)⁺ ; ¹ H NMR (CDCl₃) δminorisomer: 2.5-3.6 (m, 3H), 3.69 (s, 3H), 3.78 (s, 3H), 4.59 (t, 1H), 5.44(q, 1H), 7.81 (s, 1H), 8.34 (s, 1H); major isomer: 2.5-3.6 (m, 3H), 3.72(s, 3H), 3.80 (s, 3H), 4.17 (t, 1H), 5.07 (q, 1H), 7.93 (s, 1H), 8.37(s, 1H). The product can be taken on to the next step withoutpurification.

Step B: 9-(2',3 '-Bis(hydroxymethyl)cyclobutyl)adenine

3-(6'-Amino-9'H-purin-9'-yl)-1,2bis(carbomethoxy)cyclobutane (1.0 g,3.28 mmol) from Step A is dissolved in 50 mL of anhydrous THF under anitrogen atmosphere. To this stirred solution, at ambient temperature,is added lithium aluminum hydride to afford a white precipitate. Thismixture is stirred at ambient temperature for 1 h and then the reactionis quenched by the successive dropwise addition of 0.3 mL of water, 0.3mL of 15% aqueous sodium hydroxide solution and 0.9 mL of water. Themixture is filtered and the filter cake is washed with 50 mL of THF. Thecombined organic filtrates are dried over anhydrous sodium sulfate,filtered and concentrated to give the title compound.

EXAMPLE 703-(2'-Amino-6'-chloro-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutaneStep A: Dimethyl 3-bromocyclobutane-1,2-dicarboxylate

A solution of 5 g (51 mmol) of maleic anhydride and 0.5 mL (4 mmol) ofacetophenone in 50 mL of ethyl acetate was added to a 100 mL pyrexphotochemical reaction vessel. The vessel was sealed and purged withnitrogen for 10 min then cooled with tap water while 13.8 g (129 mmol)of vinyl bromide was being added to the ethyl acetate solution. Thevessel was then irradiated for 20 h with a 450 Watt medium pressuremercury vapor lamp. The solution was concentrated in vacuo and theresidue dissolved in 200 mL of methanol which had been treated with 1 mLof trimethylsilyl chloride. The solution was stirred at ambienttemperature overnight and then concentrated to a brown viscous oil. Theoil was chromatographed on silica gel (200 g) eluted with 20% ethylacetate in hexane to give a yellow oil. The oil was purified byshort-path distillation using a 1" fractionating column to give 2.5 g(19.5% yield) of the title compound; b.p. 75°-80° C. (0.1 mm Hg); EI-MS,m/e (rel intensity): 220 (M⁺ --CH₃ O, 60), 218 (60), 192 (42), 190 (39),171 (100); ¹ H NMR (CDCl₃) δ2.60 (m, 1H), 2.82 (m, 1H), 3.56 (td, 1H),3.72 (m, 6H), 3.94 (t, 0.4H), 4.12 (q, 0.6H), 4.93 (q, 1H).

Step B:3-(2'-Amino-6'-chloro-9'H-purin-9'-yl)-1,2-bis(carbomethoxy)cyclobutane

2-Amino-6-chloropurine (3.3 g, 19.5 mmol) was dissolved, with heating,in 100 mL of DMF under nitrogen atmosphere and the resultant solutionwas cooled to ambient temperature. Dimethyl3-bromocyclobutane-1,2-dicarboxylate (4.44 g, 17.7 mmol) from Step A wasadded via syringe, followed by 2.91 mL (19.5 mmol) of DBU and thereaction mixture was stirred overnight at ambient temperature. Thereaction was quenched in 100 mL of saturated aqueous ammonium chloridesolution and the resultant aqueous solution was extracted with 3×100 mLof ethyl acetate. The combined ethyl acetate solution was washed with3×50 mL of water and 50 mL of brine, dried over anhydrous magnesiumsulfate, filtered and concentrated to a solid residue. The residue waspurified on silica gel (250 g) eluted with 2% methanol in chloroform togive 2.65 g (44% yield) of the title compound and 0.64 g (11% yield) ofthe N-7 isomer. The ¹ H NMR spectrum was identical to the ¹ H NMRspectrum of the product of Step C of Example 68.

EXAMPLE 71 Dimethyl 3-phenylthiocyclobutane-1,2-dicarboxylate

To a solution of dimethyl maleate (0.50 mL, 4 mmol) and phenyl vinylsulfide (0.52 mL, 4 mmol) in 17 mL of 1,2-dichloroethane under nitrogenatmosphere, was added 1 equivalent (4 mL of a 1 M solution in hexane) ofethylaluminum dichloride. The resultant solution was heated at 85° C.for 18 h and then diluted with 75 mL of methylene chloride. Themethylene chloride solution was washed three times with saturatedaqueous ammonium chloride and once with brine, dried over anhydroussodium sulfate, filtered and concentrated to give 0.98 g of the titlecompound; EI-MS, m/e (rel intensity): 280 (M⁺, 14), 136 (100).

EXAMPLE 72

2,4-dioxo-6-phenylthio-3-oxabicyclo[3.2.0]heptane

To a solution of maleic anhydride (0.39 g, 4 mmol) and phenyl vinylsulfide (0.52, 4 mmol) in 17 mL of 1,2-dichloroethane under nitrogen,was added 2 mL (0.5 equiv) of ethylaluminum dichloride. The resultantsolution was stirred at ambient temperature for 0.5 h and then dilutedwith 75 mL of methylene chloride. The methylene chloride solution waswashed three times with saturated aqueous ammonium chloride solution andonce with brine, dried over anhydrous sodium sulfate and concentrated togive 0.85 g of the title compound; EI-MS, m/e (rel intensity): 234 (M⁺,23), 136 (100), 109 (12), 91 (21).

The antiviral activity of the compounds of the invention can bedetermined by the following methods.

A-1. Evaluation of Compounds for Activity Against

Herpes Simplex Virus Types 1 and Types 2

The challenge viruses were propagated and assayed in cells that werepregrown as monolayer cultures in plastic tissue culture flasks and96-well plates, using cell culture media appropriate for the host cellcultures. The following viruses and host cell cultures were employed:

    ______________________________________                                        Challenge Virus   Host Cell Type                                              ______________________________________                                        Herpes simplex type 1                                                                           Continuous passage African                                  (HSV-1) strain E-377                                                                            green monkey kidney (Vero)                                  Herpes simplex type 2                                                                           Continuous passage African                                  (HSV-2) strain MS green monkey kidney (Vero)                                  Herpes simplex type 1                                                                           Continuous passage African                                  HSV-1 strain (BW10168) TK-                                                                      green monkey kidney (Vero)                                  Herpes simplex type 2                                                                           Continuous-passage African                                  HSV-2 strain (BW9787) TK-                                                                       green monkey kidney (Vero)                                  ______________________________________                                    

On the day of use, a weighed sample of each compound to be evaluated wasdissolved and diluted in serial 10⁰.5 dilutions in the culture mediumappropriate for each virus host cell system.

CPE Inhibition Assay Procedure

Mammalian cells were pregrown as monolayers in wells of COSTAR 96-welltissue culture plates using suitable cell culture media. Stock viruseswere pretitered according to the method of Reed and Muench (Amer. J.Hyg. 27:493-497, 1938) and diluted in cell culture medium to yield 32CCID₅₀ (cell culture infectious dose, 50%) units per 0.1 ml. Antiviralassays were designed to test seven concentrations of each compound, fromcytotoxic to noncytotoxic levels, in triplicate against each of thechallenge viruses in microtiter plate wells containing suitable cellmonolayers. To each of the replicate cell cultures were added 0.1 ml ofthe test drug solution and 0.1 ml of virus suspension. Cell controlscontaining medium alone, virus controls containing medium and virus, anddrug cytotoxicity controls containing medium and each drug concentrationwere run simultaneously with the test samples assayed in eachexperiment. The covered plates were incubated at 37° C. in a humidifiedatmosphere containing 5% CO₂ until maximum CPE (cytopathogenic effect)was observed in the untreated virus control cultures. The cellmonolayers were examined microscopically for virus induced CPE and fordrug cytotoxicity.

Antiviral activity was determined by calculating the degree ofinhibition of virus induced CPE in drug treated, virus-infected cellcultures by means of a virus rating (VR). The VR is a standard weightedmeasurement of antiviral activity taking into account both the degree ofCPE inhibition and drug cytotoxicity, and is determined by amodification of the method of Ehrlich et al. (Ann. N.Y. Acad. Sci. 130:5-16, 1965) as described below. CPE was graded for each individualculture in each microtiter plate well according to the following scale:

4=100% of the cells affected by virus;

3=75% of the cells affected by virus;

2=50% of the cells affected by virus;

0=No CPE; normal cell monolayer;

The VR was calculated as 0.1 of the sum of the numerical differencesbetween the recorded CPE grade of each test well and that of thecorresponding virus control in the culture plate. Numerical differencesbetween the scores of test wells containing a drug concentration whichwas partially cytotoxic (p) and their corresponding virus controls werehalved.

The minimum inhibitory drug concentration which reduced thecytopathogenic effect (CPE) by 50% (MIC₅₀) was calculated by using aregression analysis program for semilog curve fitting. A therapeuticindex (TI) for each active compound for each susceptible virus wasdetermined by dividing the minimum cytotoxic concentration of the testcompound by the MIC₅₀. Test results are provided in Tables 1A and 1B.

A-2. Alternate Method for Evaluation of Compounds for Activity AgainstHerpes Simplex Virus Types 1 and 2

Confluent Vero cell monolayers were infected with a dilution of stockvirus which yielded approximately 100 plaque forming units (pfu) perwell. After the adsorption period, the infected cell monolayers weretreated in duplicate with serial dilutions of the test compound.Duplicate cell controls containing medium alone and virus controlscontaining medium and virus were run simultaneously with the testcompound. After incubation for 3 to 4 days to allow for the developmentof visible, discrete plaques in the untreated, virus infected controlcultures, the monolayers were fixed with formaldehyde and stained withcrystal violet. Plaques visible to the unaided eye were counted and themean number of plaques in the duplicate wells for each compoundconcentration tested and for the untreated, virus infected controls weredetermined. The concentration of test compound which reduced by 50% themean number of plaques in the untreated, virus infected control cultureswas then determined and expressed as the ID₅₀. Test results are providedin Table 1C.

B. Evaluation of Compounds for Activity Against Human ImmunodeficiencyVirus Cell Lines and Virus

The ATH8 human T-cell line expresses high levels of the CD4 surfaceantigen and is quite sensitive to the cytopathogenic effect (CPE) ofHIV. The cells were propagated in RPMI 1640 medium supplemented with 4mM glutamine, 15% heat-inactivated fetal bovine serum (Biocell),antibiotics (50 units of penicillin and 50 pg of streptomycin per ml),and 50 units of recombinant-derived human interleukin-2 (ala-125; AMGenBiologicals) per ml.

The clone H9 cell line is another CD4⁺ human T-cell line which ispermissive for HIV replication but largely resistant to virus inducedCPE. H9 cells productively infected with the HTLV-IIIB strain of HIVserved as the source of infectious virus. These cells were propagated inRPMI 1640 medium supplemented with qlutamine and antibiotics asdescribed above, and with 20% heat-inactivated fetal bovine serum.Freshly harvested, undiluted culture supernatant from the H9/HTLV-IIIBproducer cells was used for infectious virus inoculum. Culturesupernatant collected 48 hours post cell passage showed the bestinfectivity.

CPE Inhibition Assay

The screening of compounds for antiviral activity was performed using amodification of the CPE-inhibition assay originally developed by Broderand co-workers. This assay is based on the ability of uninfected ATH8cells to grow and form a pellet at the bottom of a culture tube.Starting about 4 days after HIV addition, infected ATH8 cells begin todie and the pellet starts to break up. By day 10 a clear differential isobservable in the size of the cell pellet in uninfected control wellsversus infected control wells. The protective effect of test compoundscan be assessed by adding them at varying concentrations to the culturedcells at the time of virus infection, then monitoring the status of thecell pellet.

ATH8 cells were used as the primary target in the HIV induced CPEinhibition assay. Cells were treated with polybrene (2 ug/ml in growthmedium) for 30 minutes at 37° C., then collected by gentlecentrifugation (40×g for 15 minutes at room temperature) and resuspendedin clarified (8000×g for 15 minutes at 4° C.) supernate freshlyharvested from 48 hours post-passage H9/HTL-III_(B) cells. Following a60 minute adsorption period at 37° C., the cells were dispensed into theU-bottom wells of 96-well trays (1×10⁴ cells in 0.1 ml per well). Anequal volume (0.1 ml) of supplemented RPMI 1640 medium containing testcompound and twice the normal concentration of interleukin-2 was thenadded to each well. Test compounds were evaluated at seven half-logdilutions ranging from 100 ug/ml to 0.1 ug/ml Triplicate virus infectedcultures and one uninfected compound cytotoxicity control culture wereincluded at each concentration. Cultures were incubated at 37° C. in ahumidified atmosphere of 5% CO2 in air.

Between 7 and 10 days post infection, all wells were visually monitoredfor the degree of CPE-inhibition as reflected by cell pellet size, andaliquots were taken from selected wells for determination of cell numberand viability (based on trypan-blue dye exclusion). Test results areprovided in Table 2.

C-1. Alternate Method for Evaluation of Compounds for Activity AgainstHuman Immunodeficiency Virus

The method of Mitsuya and Broder (AIDS: Modern Concepts and TherapeuticChallenges; Broder, S. ED.; Marcel Dekker, Inc.; New York, 1987; Chapter18) was used to determine the in vitro anti-HIV-1 and anti HIV-2activity in ATH8 cells of some compounds of the invention. The resultsof the test are expressed as the percentage of ATH8 cells that wereprotected from the cytopathogenic effects of HIV at variousconcentrations of the compound of the invention. Test results areprovided in Tables 3A and 3B.

C-2. Alternate Method for In Vitro Evaluation of Compounds forAnti-HIV-1/2 Activity

Uninfected H9 cells at 4×10⁵ viable cells/ml were infected withapproximately 100 viral infectious units (ifu) for 2 hrs at 37° C. Theviral infectious dose (ifu) was determined by the tissue cultureinfectious dose (TCID₅₀) method for each stock of HIV-1 (HTLV-IIIB) andHIV-2. Cells were washed three times to remove residual virus, thenresuspended in RPMI-1640 growth medium containinmq test compound atvarious concentrations, then transferred to 24 well tissue cultureplates and grown at 5% CO₂ at 37° C. Infected cells in media containingno drug were run simultaneously as a control. Aliquots of culturesupernatants were removed at 4, 6 and 10 days and monitored for HIVantigen levels by the Abbott HIV-1 antigen enzyme immunoassy (HIVAG-1).Cell viability was also determined at these time points and cells wererefed with media containing test compound (except for control wells).Anti-HIV acitivity is reported as the concentration of compound causinga 50% inhibition (IC₅₀) in HIV antigen levels versus infected cellswithout test compound. Test results are provided in Table 3C.

C-3. Method for Evaluation of the Activity of Compounds Against HIV inPBMC's Cells

Human peripheral blood mononuclear cells (PBMC) from healthy HIV-1seronegative and hepatitis B virus seronegative donors were isolated byFicoll-Hypaque discontinuous gradient centrifugation at 1,000×g for 30minutes, wahed twice in phosphate buffered saline (pH 7.2; PBS), andpelleted at 300×g for 10 minutes. Before infection, the cells werestimulated by phytohemagglutinin (PHA) at a concentration of 16.7 ug/mlfor three days in RPMI 1640 medium supplemented with 15%heat-inactivated fetal calf serum, 1.5 mM L-glutamine, penicillin (100U/ml), streptomycin (100 ug/ml) and 4 mM sodium bicarbonate buffer.

Inhibition of Virus Replication in Human PBMC

Uninfected PHA-stimulated human PBMC were uniformly distributed among 25cm² flasks to give a 5 ml suspension containing about 2×10⁶ cells/ml.Suitable dilutions of virus were added to infect the cultures. The meanreverse transcriptase (RT) activity of the inocula was 60,000 dpm RTactivity/10⁶ cells. The test compounds at twice their finalconcentrations in 5 ml of RPMI 1640 medium, supplemented as describedabove, were added to the cultures. Uninfected and untreated PBMC atequivalent cell densities were grown in parallel as controls. Thecultures were maintained in a humidified 5% CO₂ -95% air incubator at37° C. for six days after infection at which point all cultures weresampled for supernatant RT activity.

RT Activity Assay

Six milliliter supernatant from each culture was clarified from cells at300×g for 10 minutes. Virus particles were pelleted from 5 ml samples at40,000 rpm for 30 minutes using a Beckman 70.1 Ti rotor and suspended in200 ul of virus disrupting buffer (50 mM Tris HCl, pH 7.8, 800 mM NaCl,20% glycerol, 0.5 mM phenylmethyl sulfonyl fluoride and 0.5% TritonX-100).

The RT assay was perfromed in 96-well microtiter plates as described bySpira, et al. (J. Clin. Microbiol. 25 97 (1987)). The reaction mixture,which contained 50 mM Tris-HCl pH 7.8, 9 mM MgCl₂, 5 mM dithiotreitol,4.7 ug/ml (rA)_(n).(dT)₁₂₋₁₈, 140 uM DATP, and 0.22 uM [³ H]TTP(specific activity 78.0 Ci/mmol, equivalent to 17,300 cpm/pmol); NENResearch Products, Boston, Mass.) was added to each well. The sample (20ul) was added to the reaction mixture which was then incubated at 37° C.for 2 hours. The reaction was terminated by the adition of 100 ul 10%trichloroacetic acid (TCA) containing 0.45 mM sodium pyrophosphate. Theacid insoluble nucleic acids which precipitated were collected onglassfilters using a Skatron semi automatic harvester (setting 9). Thefilters were washed with 5% TCA and 70% ethanol, dried and placed inscintillation vials. Four ml of scintillation fluid (Econofluor, NENResearch Products, Boston, Mass.) were added and the amount ofradioactivity in each sample was determined using a Packard Tri-Carbliquid scintillation analyzer (model 2,000CA). The results wereexpressed in dpm/ml of original clarified supernatant. The proceduresfor the anti-HIV-1 assays in PBMC described above have been published(Antimicrob. Agents Chemother. 32 1784 (1988)).

Median-effect Method

EC₅₀ values were obtained by analysis of the data using themedian-effect equation (Chou, et al., Adv. Enz. Regul. 22 27 (1984)).The results of this test are provided in Table 3D.

Cytotoxicity

The test compounds were evaluated for their potential toxic effects onuninfected PHA-stimulated human PBM cells. The cells were cultured withand without test compound for 6 days at which time aliquots were countedfor cell viability.

D. Evaluation of Compounds for Activity Against Human Cytomegalovirus(HCMV)--Virus Yield Reduction Assay

Human diploid embryonic lung (MRC5) cells were grown in 35 mm wells of6-well tissue culture plates. Subconfluent cell monolayers were rinsedwith phosphate-buffered saline (PBS) and were exposed to 0.5 ml/well ofHCMV (strain AD169) suspension for 1.5 hours at 37° C. The virussuspension was diluted in MEM +2% fetal bovine serum (FBS) to yield amultipicity of infection (MOI) of approximately 0.1 plaque forming units(PFU)/cell. Following the virus adsorption period, the inocula wereremoved and infected cell layers were rinsed with PBS. Aliquots (2.0 ml)of each test drug concentration (dissolved in MEM supplemented with 2%FBS) were dispensed into triplicate cell cultures: two virus-infectedcultures and one uninfected cytotoxicity control culture (exposed tomedium without virus for 1.5 hours). Untreated virus-infected controlcultutres and untreated, uninfected cell control cutures were fed withmedium alone. The culture plates were incubated at 37° C. in ahumidified atmosphere of 2% CO₂ in air.

All cell culture fluids were replaced with fresh drug and medium 48hours postinfection (p.i.).

On Day 6 p.i., the cell layers were examined microscopically forcytopathogenic effect (CPE) and drug cytotoxicity. The test and viruscontrol cultures were then harvested by subjecting the cell layers toone cycle of freeze-thawing. The cellular material was scraped into theambient medium and the contents from replicate cultures were pooled,dispensed into cryotubes and stored at -135° C.

Drug cytotoxicity was determined quantitatively by a method based on thereduction of the tetrazolium salt,3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) bymitochondrial enzymes of viable host cells to MTT formazan (T. Mosmann,1983). Drug cytotoxicity controls and cell controls were treated withMTT (dissolved in culture medium) followed by 20% SDS (in 0.02 N HCl) todissove the crystals of MTT formazan. The blue color of the MTT formazanwas measured spectrophotometrically at 570 nm. Drug cytotoxicity wasdetermined by comparing the absorbance (O.D.) of each drug cytotoxicitycontrol with the mean O.D. of the cell control cultures and expressed aspercent of control.

The harvested test and virus control samples were thawed and theinfectious virus yield was determined by plaque assay in MRC5 cellsgrown in 12-well cluster plates. Inhibiton of HCMV replication by eachtest compound was determined by comparing the progeny virus yields inthe drug-treated cultures with the progeny virus yield in the untreated,virus-infected control cultures. Test results are provided in Table 4.

E. Evaluation of Compounds for In Vivo Activity Against Herpesvirus 1 inMice

Four-week-old female outbred Swiss mice (CD-1, VAF+, Charles River Labs)were housed 5 per Microisolator® cage. Feed and water were supplied adlibitum. Fifteen mice were randomly assigned to each of the followingtreatment groups:

1. untreated controls

2. diluent (0.4% CMC/PBS controls)

3. 100 mg/kg test compound

4. 32 mg/kg test compound

5. 10 mg/kg test compound

6. 3.2 mg/kg test compound

Test compounds were diluted in 0.4% caboxymethylcellulose (CMC) preparedin phosphate buffered saline (PBS) at aconcentrations consistent withdosing at 0.1 ml per 10 g of body weight. Compounds were administeredsubcutaneously once daily for a total of 7 doses. Five mice in eachtreatment group served as uninfected toxicity controls. The remainingten mice in each group were challenged intraperitoneally with an LD₉₀dose of the twelfth in vivo passage of Herpesvirus 1 (strain 123). Viruschallenge was administered two hours after the first dose of compoundwas given. Mortality was monitored daily for 21 days. The mortalityrates, average day of death, geometric mean time to death and virusrating were calculated for each treatment group. The results of thistest are presented in Table 5.

F. Evaluation of Compounds for Efficacy Against Hepatitis B Virus InVivo in Ducklings

The test method is an adaptation of the method of Smee, et al.,Antimicrob. Agents Chemotherap. 27 277 (1985). The serum level of duckhepatitis B virus (DHBV) DNA was monitored in 6 infected Pekinoducklings from age 6 days to age 27 days. Four ducklings were treatedwith 70 mg/kg/day IP, b.i.d. of the test compound as a 3 mg/ml solutionin 0.9% aqueous NaCl on days 10-17. Two control ducklings were treatedwith 23 ml/kg/day IP, b.i.d. of 0.9% aqueous NaCl on days 10-17. Thelevel of DHBV DNA in the duckling serum was measured daily. The resultsof this test are presented in Table 6.

G. Evaluation of Compounds for Activity Against Epstein-Barr Virus (EBV)In Vitro

Virus producing cells (P3HR-1) were exposed to test compound for 14 daysand EBV genome copies per cell were determined by EBV-specific cRNA-DNAhybridization (Lin, et al., J. Virology 50 50-55 (1984). The results ofthis test are presented in Table 7.

H. Evaluation of Compounds for Selective Inhibition of Varicella-ZosterVirus Plaque Formation in Cell Culture

For the plaque reduction assay, secondary human foreskin fibroblastswere seeded in wells of 12-well tissue culture plates and incubated at37° C. in a humidified atmosphere containing 2% CO₂ in air. SubconfluentHFF were rinsed with MEM and exposed to 0.25 ml/well of a suspension ofVSV (a clinical isolate designated DM625 obtained from Dr. RichardWhitley of the University of Alabama Hospitals, Birmingham, Ala.)diluted in MEM+2% FBS for 2 hours at 37° C. Following the virusadsorption period, the inocula were removed and infected cell layerswere rinsed with MEM. Triplicate VZV infected cell culture wells weretreated with 1.0 ml of each test compound concentration (in MEM +2%FBS). Six untreated virus infected cell cultures and triplicateuntreated uninfected cell cultures were fed with 1.0 ml of MEM+2% FBS toserve as controls. Wells containing uninfected HFF were treated witheach test compound concentration to monitor the cytotoxicity of the testcompounds. The 12-well plates were incubated at 37° C. in the CO₂incubator. At 48 hours postvirus infection (p.i.) fluids were replcaedwith fresh test compound and/or culture medium.

Five days p.i. the VZV plaques were counted (unstained, using lowmagnification). The effect of each test compound concentration on plaqueformation was determined by comparing the mean number of plaques in thereplicate drug-treated cultures with the mean plaque counts of theuntreated virus control cultures.

The test compound cytotoxicity control cutures were examinedmicroscopically for gross morphologic changes, then treated with MTT and20% SDS. The blue color of the MTT formazan was measuredspectrophotometrically at 570 nm. Drug cytotoxicity was determined bycomparing the absorbance (O.D.) of each test compound cytotoxicitycontrol with the mean O.D. of the cell control cultures and expressed aspercent of control. Test results are provided in Table 8.

I. Evaluation of Compounds for Cytotoxic Activity Against Cultured TumorCells

Test compunds were dissolved in DMSO, ethanol, water or other suitablesolvent. This stock solution was diluted in culture medium to twice thehighest concentration to be tested. From this 2×stock, two-fold serialdilutions were prepared in 96-well microtiter trays, each wellcontaining twice the desired final concentration. Each concentration wastested in triplicate and compared to triplicate drug-free controls.

Cells were grown and tested in RPMI 1640 supplemented with 10% fetalcalf serum. After harvesting, viable cell counts were determined byhemacytometer or coulter counter and cell density was adjusted to 25,000per milliliter. One tent milliliter of inoculum was added to each wellfor a final concentration of 2,500 cells per well. Addition of theinoculum dilutes the test compunds to the desired final concentration.

Microtiter trays were incubated for three days at 37° C. in a humidifiedatmosphere containing 5% CO₂.

After three days, 20 ul of 5 mg/ml MTT in phosphate buffered saline (pH7.2) was added to each well. Trays were returned to the incubator forninety minutes to allow the surviving cells to reduce the dye. Mediumand unreduced dye were removed by aspiration or inversion. DMSO wasadded to each well to dissolve the water insoluble, colored end-productof the dye reducton. Absorbance was measured spectrophotometrically at570 nm. This method is a modification of the method reported by Mosmann,J. Immunol. Meth., 65 55 (1983). Test results are provided in Table 9.

                                      TABLE 1A                                    __________________________________________________________________________    Antiviral Activity of Compounds of Formula I                                  Against Herpes Simplex                                                        Challenge Virus:                                                                       Herpes Simplex  Herpes Simplex                                                Type 1 (E- 377) Type 2 (MS)                                          Host Cell Type:                                                                        Vero            Vero                                                 Compound of                                                                   Example No.                                                                            VR.sup.1                                                                         ID50.sup.2                                                                        MTC.sup.3                                                                          TI.sup.4                                                                          VR ID50                                                                              MTC  TI                                       __________________________________________________________________________     1I      5.7                                                                              1.5 320  213 4.1                                                                              6.4 320  50                                                5.1                                                                              2.5 320  129 3.4                                                                              10.6                                                                              320  30                                        1H      1.5                                                                              83  320  3.9 0.6                                                                              179 320  1.8                                               1.4                                                                              89  320  3.6 0.5                                                                              217 320  1.5                                       3       3.6                                                                              10.07                                                                             320  31.8                                                                              2.0                                                                              50.5                                                                              320  6.34                                      4C      2.1                                                                              8.7  32  3.7 1.8                                                                              18.1                                                                              100  5.5                                       5G      2.1                                                                              146 >320 >2.2                                                                              0.9                                                                              --  >320 >1.0                                      6       2.4                                                                              31.7                                                                              320  10.1                                                                              1.6                                                                              71.8                                                                              320  4.5                                       7        0.55                                                                            270.9                                                                             320  1.2                                                       8E      0.9                                                                              --  320  --   1.35                                                                            54.7                                                                              100  1.8                                      20       2.2                                                                              12.1                                                                              100  8.2 1.9                                                                              15.7                                                                              100  6.4                                      21       1.0                                                                              88  320  3.6 1.2                                                                              75  320  4.3                                      23       1.7                                                                              100 >320 3.2 0.7                                                                              --  >320 --                                       67C      1.2                                                                              11.1                                                                               32  2.9 0.9                                                                              14.9                                                                               32  2.1                                      __________________________________________________________________________

                                      TABLE 1B                                    __________________________________________________________________________    Antiviral Activity of Compounds of Formula I                                  Against Herpes Simplex                                                        Challenge Virus:                                                                       Herpes Simplex  Herpes Simplex                                                Type 1 (BW10168) TK-                                                                          Type 2 (BW9787) TK-                                  Host Cell Type:                                                                        Vero            Vero                                                 Compound of                                                                   Example No.                                                                            VR.sup.1                                                                         ID50.sup.2                                                                        MTC.sup.3                                                                          TI.sup.4                                                                          VR ID50                                                                              MTC  TI                                       __________________________________________________________________________     1I      3.3                                                                              4.06                                                                              100  24.6                                                                              5.4                                                                              0.79                                                                              100  127                                      __________________________________________________________________________     .sup.1 VR = Virus Rating: A measurement of selective antiviral activity       which takes into account the degree of virus induced cytopathogenic           effects (CPE) and the degree of cytotoxicity produced by the test             compound, determined by a modification of the method of Ehrlich et al.        (Ann. N.Y. Acad. Sci. 130: 5-16, 1965). A VR > 1.0 indicates definite (+)     antiviral activity, a VR of 0.5-0.9 indicates marginal to moderate            antiviral activity, and a VR < 0.5 usually indi cates no significant          antiviral activity.                                                           .sup.2 ID50 = The minimum drug concentration (ug/ml) that inhibited the       CPE by 50%, calculated by using a regression analysis program for semilog     curve fitting.                                                                .sup.3 MTC = The minimum drug concentration (ug/ml) causing any               cytotoxicity.                                                                 .sup.4 TI = Therapeutic Index, calculated by dividing the minimum             cytotoxic drug concentration by the ID50.                                     The results indicate that the compounds are active against HSV1 and HSV2.

                  TABLE 1C                                                        ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Herpes Simplex                                                        Challenge Virus:                                                                         HSV-1 (E-377)                                                                             HSV-1 (123) HSV-2                                      Host Cell Type:                                                                          Vero        Vero        Vero                                       Compound of                        MIC50                                      Example No.                                                                              MIC50 (ug/ml)                                                                             MIC50 (ug/ml)                                                                             (ug/ml)                                    ______________________________________                                         1I        0.5         1.0         1.0                                        42P        1.0         3.0         1.0                                        ______________________________________                                         The results indicate that the compounds are active against HSV1 and HSV2.

                  TABLE 2                                                         ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Immunodeficiency Virus (HIV)                                    In ATH8 Cells**                                                               Compound of                                                                   Example No.                                                                            Protocol    VR      ID50  MTC    TI                                  ______________________________________                                        4B       CPE Inhibition                                                                            1.1     --    10.0   --                                  4C       CPE Inhibition                                                                            3.5     <0.1   3.2   32                                  ______________________________________                                         **Using method of section B from above                                   

                  TABLE 3A                                                        ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Immunodeficiency Virus (HIV-1)                                  In ATH8 Cells**                                                                        Concentration                                                                             Protective                                               Compound (uM)        Effect (%)                                                                              Cytotoxicity (%)                               ______________________________________                                        Ex. 1I    1          51         0                                                       10         90         0                                             Ex. 4C    1          48        12                                                       10         63        33                                                      100         76        34                                             Ex. 6     1          21         0                                                       10         48         4                                                      100         46        32                                                      500         57        38                                             ______________________________________                                         **Using method of section C from above                                   

                  TABLE 3B                                                        ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Immunodeficiency Virus (HIV-2)                                  In ATH8 Cells**                                                                        Concentration                                                                             Protective                                               Compound (uM)        Effect (%)                                                                              Cytotoxicity (%)                               ______________________________________                                        Ex. 1I    1          24        11                                                      10          65        11                                             Ex. 4C    1          33         9                                                      10          70        15                                             ______________________________________                                         **Using method of section C from above                                   

The results indicate that the compounds are active against HIV-2 and/orHIV-1.

                  TABLE 3C                                                        ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Immunodificiency Virus (HIV-1)                                  in H9 Cells                                                                            Concentration                                                        Compound (uM)         % Inhibition                                                                              IC.sub.50 (uM)                              ______________________________________                                        Ex. 4C   10           98          2.1                                                  5            96                                                               2.5          62                                                               0.625         0                                                      Ex. 1I   10           88          1.1                                                  2.5          75                                                               1.25         63                                                               0.625        19                                                               0.312         0                                                      ______________________________________                                    

The results indicate that the compounds are active against HIV-1.

                  TABLE 3D                                                        ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Immunodificiency Virus (HIV-1)                                  in PBMC Cells                                                                 Compound EC.sub.50 (uM)                                                                           Cytotoxicity in PBMC IC.sub.50 (uM)                       ______________________________________                                        Ex. 4C   0.96       23                                                        Ex. 1I   0.98       38.8                                                      ______________________________________                                    

The results indicate that the compounds are active against HIV-1.

                  TABLE 4                                                         ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Human Cytomegalovirus (HCMV)                                          In MRC5 Cells                                                                                 HCMV                                                                 Drug     yield     HCMV yield MTT assay                                Com-   Conc.    (log10    reduction  Percent of                               pound  (ug/ml)  PFU/ml)   (log10 PFU/ml)                                                                           control                                  ______________________________________                                        Ex. 1I 1.0      3.12      1.15       100                                             3.2      2.43      1.84       100                                             10       1.63      2.64       100                                             32       <0.6*     >3.7       100                                      Ex. 4C 0.32     3.3       1.4                                                        1.0      2.6       2.1                                                        3.2      <0.6      >4.1       95                                              10       <0.6      >4.1       90                                              32       <0.6      >4.1       67                                       Ex. 67B                                                                              3.2      4.9       0.4        --                                              10       4.0       1.3        86                                              32       3.1       2.2        68                                       Virus  0        4.27                                                          control                                                                       ______________________________________                                         *below limit of detection                                                

The results indicate that the compound is active against HCMV.

                                      TABLE 5                                     __________________________________________________________________________    Antiviral Efficacy of Compounds of Formula I                                  Against Intraperitoneal Challenge with                                        Herpesvirus 1 in Mice                                                                  Dose                                                                              No. Dead/                                                                             No. Dead/                                                Compound mg/kg                                                                             No. Uninfected                                                                        No. Infected                                                                         GMTD*                                                                              VR**                                         __________________________________________________________________________    untreated    0/5     10/10  8.8  NA                                           0.4% CMC/PBS 0/5     10/10  8.3  NA                                           Example 1I                                                                             3.2 0/5     8/10   10.8 1.3                                                   10  0/5     5/10   13.0 1.6                                                   32  0/3     0/10   21.0 2.5                                          __________________________________________________________________________     *GMTD = geometric mean time to death                                          **VR (virus rating) = GMTD of experimental/GMTD of diluenttreated control

The results indicate that the compounds is active in vivo againstHerpesvirus 1.

                                      TABLE 6                                     __________________________________________________________________________    Antiviral Efficacy of Compounds of Formula I                                  Against Hepatitis B Virus in Ducklings                                                           Serum DHBV                                                                    DNA (ng/ml)                                                       Age of Ducks                                                                         Adminis-                                                                           Duck #                                                     Compound                                                                             (days) tration                                                                            1  2  3  4  (5)                                                                              (6)                                         __________________________________________________________________________    Example                                                                               6          187                                                                              143                                                                              520                                                                              288                                                                              518                                                                              206                                         1I      7          156                                                                              111                                                                              311                                                                              215                                                                              513                                                                              200                                                 8          168                                                                              121                                                                              277                                                                              256                                                                              228                                                                              103                                                 9          233                                                                              102                                                                              412                                                                              311                                                                              300                                                                              147                                                10     *    213                                                                              120                                                                              377                                                                              333                                                                              310                                                                              155                                                11     *    155                                                                              61 130                                                                              132                                                                              304                                                                              69                                                 12     *    64 27 77 21 119                                                                              35                                                 13     *    11 2  16 2  85 43                                                 14     *    6  1  2  1  62 27                                                 15     *    <1 <1 2  1  48 39                                                 16     *    <1 <1 <1 1  24 48                                                 17     *    <1 <1 <1 <1 107                                                                              16                                                 18          <1 <1 <1 <1 146                                                                              21                                                 19          <1 <1    <1 155                                                                              12                                                 20          <1 <1    <1 190                                                                              62                                                 21          <1 <1    <1 221                                                                              190                                                22          3  <1    <1 297                                                                              196                                                23          12 <1    <1 266                                                                              200                                                24          16 <1    <1 175                                                                              182                                                25          31 2     <1 192                                                                              323                                                26          71 2        283                                                                              340                                                27          134                                                                              7        357                                                                              263                                         __________________________________________________________________________     Remark: ducks 3 and 4 died on day 18 and day 26, respectively. Ducks (5)      and (6) are the saline treated, placebo controls.                        

The results indicate that the compound is active against hepatitis Bvirus in vivo.

                  TABLE 7                                                         ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Epstein-Barr Virus In Vitro                                           Compound concentration (uM)                                                                          EBV genome copies/cell                                 ______________________________________                                        Example 1I                                                                             0.01          223                                                             0.10          181                                                             1.00          40                                                              5.00          12                                                              10.00         10                                                              50.00         **                                                     control                214                                                    ______________________________________                                         **This drug concentration was toxic.                                     

The results indicate that the compound is active against Epstein-Barrvirus.

                  TABLE 8                                                         ______________________________________                                        Antiviral Activity of Compounds of Formula I                                  Against Varicella-Zoster Virus Plaque Formation                               in Human Foreskin Monolayer Cultures                                                  Concen-                                                                       tration   Plaque     MTT Assay MIC.sub.50                             Compound                                                                              ug/ml     Reduction %                                                                              (% of control)                                                                          ug/ml                                  ______________________________________                                        1I      100       100        62        1.4                                            32        100        72                                                       10        100        76                                                       3.2       97.7       79                                                       1.0       47.1       --                                                       0.32      18.0       --                                                       0.1       11.5       --                                               ______________________________________                                         Average number of plaques in untreated virus control cultures = 87       

The results indicate that the compound is active againstVaricella-Zoster virus.

                  TABLE 9                                                         ______________________________________                                        Antitumor Activity of Compounds of Formula I                                  Against Cultured Tumor Cells                                                  Cell Line:                                                                             A549        HCT-8       P388-D1                                      Compound IC50 (ug/ml)                                                                              IC50 (ug/ml)                                                                              IC50 (ug/ml)                                 ______________________________________                                         4C      49.1        71.4        0.64                                          1I      94.6        >100        2.8                                          67B      18.8        0.63        4.9                                          67F      3.1         5.9         5.2                                          67C      18.4        4.3         16.4                                         ______________________________________                                         IC50: The concentration of test compound needed to reduce the absorbance      at 570 nm in a colorimetric assay by 50%                                      A549: Lung carcinoma, Human (acquired from ATCC, Catalog #CCL 185)            HCT8: Adenocarcinoma, ileocecal, Human (acquired from ATCC, Catalog #CCL      244)                                                                          P388D1: (Mouse, Lymphocytic Leukemia) (acquired from ATCC, Catalog #CCL       46)                                                                      

The results indicate that the compounds are active against the indicatedtumors.

The compounds of the present invention can be used in the form of saltsderived from inorganic or organic acids. These salts include but are notlimited to the following: acetate, adipate, alginate, citrate,aspartate, benzoate, benzenesulfonate, bisulfate, butyrate, camphorate,camphorsulfonate, digluconate, cyclopentanepropionate, dodecylsulfate,ethanesulfonate, glucoheptonate, glycerophosphate, hemisulfate.heptonate, hexanoate, fumarate, hydrochloride, hydrobromide,hydroiodide, 2-hydroxy ethanesulfonate, lactate, maleate,methanesulfonate, nicotinate, 2-naphthalenesulfonate, oxalate, pamoate,pectinate, persulfate, 3-phenylpropionate, picrate, pivalate,propionate, succinate, tartrate, thiocyanate, tosylate, and undecanoate.Also, the basic nitrogen-containing groups can be quaternized with suchagents as loweralkyl halides, such as methyl, ethyl, propyl, and butylchloride, bromides, and iodides; dialkyl sulfates like dimethyl,diethyl, dibutyl, and diamyl sulfates, long chain halides such as decyl,lauryl, myristyl and stearyl chlorides, bromides and iodides, aralkylhalides like benzyl and phenethyl bromides, and others. Water oroil-soluble or dispersible products are thereby obtained.

Examples of acids which may be employed to form pharmaceuticallyacceptable acid addition salts include such inorganic acids ashydrochloric acid, sulphuric acid and phosphoric acid and such organicacids as oxalic acid, maleic acid, succinic acid and citric acid. Othersalts include salts with alkali metals or alkaline earth metals, such assodium, potassium, calcium or magnesium or with organic bases.

The novel compounds of the present invention possess antiviral activityand are useful for treating or preventing virus related diseases.Compounds of the invention are effective against herpes simplex viruses,human cytomegalovirus, hepatitis B virus, Epstein-Barr virus andVaricella Zoster virus.

Total daily dose administered to a host in single or divided doses maybe in amounts, for example, from 0.1 to 2000 mg/kg body weight daily andmore usually 1.0 to 500 mg/kg. Dosage unit compositions may contain suchamounts of submultiples thereof to make up the daily dose.

The amount of active ingredient that may be combined with the carriermaterials to produce a single dosage form will vary depending upon thehost treated and the particular mode of administration.

It will be understood, however, that the specific dose level for anyparticular patient will depend upon a variety of factors including theactivity of the specific compound employed, the age, body weight,general health, sex, diet, time of administration, route ofadministration, rate of excretion, drug combination, and the severity ofthe particular disease undergoing therapy.

The compounds of the present invention may be administered orally,parenterally, by inhalation spray, rectally, or topically in dosage unitformulations containing conventional nontoxic pharmaceuticallyacceptable carriers, adjuvants, and vehicles as desired. Topicaladministration may also involve the use of ointments, creams orophthalmically acceptable solutions, suspensions, emulsions, ointmentsand solid inserts. The term parenteral as used herein includessubcutaneous injections, intravenous, intramuscular, intrasternalinjection, or infusion techniques.

Injectable preparations, for example, sterile injectable aqueous oroleagenous suspensions may be formulated according to the known artusing suitable dispersing or wetting agents and suspending agents. Thesterile injectable preparation may also be a sterile injectable solutionor suspension in a nontoxic parenterally acceptable diluent or solvent,for example, as a solution in 1,3-butanediol. Among the acceptablevehicles and solvents that may be employed are water, Ringer's solution,and isotonic sodium chloride solution. In addition, sterile, fixed oilsare conventionally employed as a solvent or suspending medium. For thispurpose any bland fixed oil may be employed including synthetic mono- ordiglycerides. In addition, fatty acids such as oleic acid find use inthe preparation of injectables.

Suppositories for rectal administration of the drug can be prepared bymixing the drug with a suitable nonirritating excipient such as cocoabutter and polyethylene qlycols which are solid at ordinary temperaturesbut liquid at the rectal temperature and will therefore melt in therectum and release the drug.

Solid dosage forms for oral administration may include capsules,tablets, pills, powders, and qranules. In such solid dosage forms, theactive compound may be admixed with at least one inert diluent such assucrose lactose or starch. Such dosage forms may also comprise, as isnormal practice, additional substances other than inert diluents, e.g.,lubricating agents such as magnesium stearate. In the case of capsules,tablets, and pills, the dosage forms may also comprise buffering agents.Tablets and pills can additionally be prepared with enteric coatings.

Liquid dosage forms for oral administration may include pharmaceuticallyacceptable emulsions, solutions, suspensions, syrups, and elixirscontaining inert diluents commonly used in the art, such as water. Suchcompositions may also comprise adjuvants, such as wetting agents.emulsifying and suspending agents, and sweetening, flavoring, andperfuming agents.

The foregoing is merely illustrative of the invention and is notintended to limit the invention to the disclosed compounds. Variationsand changes which are obvious to one skilled in the art are intended tobe within the scope and nature of the invention which are defined in theappended claims.

What is claimed is:
 1. A compound of the formula: ##STR21## wherein A is##STR22## E is hydrogen, --CH₂ OH or --OH; and G and D are independentlyselected from hydrogen, C₁ to C₁₀ alkyl, --OH, --CH₂ OH, --CH₂ OR₂₀wherein R₂₀ is C₁ to C₆ alkyl, --CH₂ OC(O)R₂₁ wherein R₂₁ is C₁ to C₁₀alkyl, --CH₂ OC(O)CH(R₂₂) (NHR₂₃) wherein R₂₂ is the side chain of anyof the naturally occuring amino acids and R₂₃ is hydrogen or--C(O)CH(R₂₄) (NHR₂) wherein R₂₄ is the side chain of any of thenaturally occuring amino acids, --CH₂ SH, --CH₂ Cl, CH₂ F, --CH₂ Br,--CH₂ I, --C(O)H, --CH₂ CN, --CH₂ N₃, --CH₂ NR₁ R₂, --CO₂ R₁, --CH₂ CH₂OH, --CH₂ CH₂ OR₂₀ wherein R₂₀ is as defined above, --CH₂ CH₂ OC(O)R₂₁wherein R₂₁ is as defined above, -- CH₂ CH₂ OC(O)CH(R₂₂) (NHR₂₃) whereinR₂₂ and R₂₃ are as defined above, --CH₂ CH₂ PO₃ H₂, --CH₂ OPO₃ H₂,--OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃ wherein R₁ and R₂ are independentlyselected from hydrogen and C₁ to C₁₀ alkyl, --NHC(O)R₃ wherein R₃ ishydrogen, C₁ to C₁₀ alkyl, carboxyalkyl or aminoalkyl, --N═CHNR₄ R₅wherein R₄ and R₅ are independently selected from C₁ to C₁₀ alkyl,--N(R₆)OR₇ wherein R₆ and R₇ are independently selected from hydrogenand C₁ to C₁₀ alkyl, and --N(R₈)NR₉ R₁₀ wherein R₈, R₉ and R₁₀ areindependently selected from hydrogen and C₁ to C₁₀ alkyl, with theprovide that when E is --OH then D is not --OH and with the proviso thatwhen E is hydrogen and D is hydrogen or C₁ to C₁₀ alkyl then G is nothydrogen or C₁ to C₁₀ alkyl; or a pharmaceutically acceptable saltthereof.
 2. A compound of the formula: ##STR23## wherein A is ##STR24##E is hydrogen, --CH₂ OH or --OH; and G and D are independently selectedfrom hydrogen, C₁ to C₁₀ alkyl, --OH, --CH₂ OH, --CH₂ OR₂₀ wherein R₂₀is C₁ to C₆ alkyl, --CH₂ OC(O)R₂₁ wherein R₂₁ is C₁ to C₁₀ alkyl, --CH₂OC(O)CH(R₂₂) (NHR₂₃) wherein R₂₂ is the side chain of any of thenaturally occuring amino acids and R₂₃ is hydrogen or --C(O)CH(R₂₄)(NH₂) wherein R₂₄ is the side chain of any of the naturally occuringamino acids, --CH₂ SH, --CH₂ Cl, --CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H,--CH₂ CN, --CH₂ N₃, --CH₂ NR₁ R₂, --CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₂₀wherein R₂₀ is as defined above, --CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is asdefined above, --CH₂ CH₂ OC(O)CH(R₂₂) (NHR₂₃) wherein R₂₂ and R₂₃ are asdefined above, --CH₂ CH₂ PO₃ H₂, --CH₂ OPO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂CO₂ R₃ wherein R₁ and R₂ are independently selected from hydrogen and C₁to C₁₀ alkyl, --NHC(O)R₃ wherein R₃ is hydrogen, C₁ to C₁₀ alkyl,carboxyalkyl or aminoalkyl, --N═CHNR₄ R₅ wherein R₄ and R₅ areindependently selected from C₁ to C₁₀ alkyl, --N(R₆)OR₇ wherein R₆ andR₇ are independently selected from hydrogen and C₁ to C₁₀ alkyl, and--N(R₈)NR₉ R₁₀ wherein R₈, R₉ and R₁₀ are independently selected fromhydrogen and C₁ to C₁₀ alkyl, with the proviso that when E is --OH thenD is not --OH and with the proviso that when E is hydrogen and D ishydrogen or C₁ to C₁₀ alkyl then G is not hydrogen or C₁ to C₁₀ alkyl;and with the proviso that when E is hydrogen and G is --OH, then D isother that --CH₂ OH, --CH₂ OC(O)R₂₁ or --CH₂ OPO₃ H₂ or apharmaceutically acceptable salt thereof.
 3. A compound of the formula##STR25## wherein A is ##STR26## E is hydrogen; and G is --OH and D is--CH₂ OH, --CH₂ OC(O)R₂₁ wherein R₂₁ is C₁ to C₁₀ alkyl or --CH₂ OPO₃ H₂; or a pharmaceutically acceptable salt thereof.
 4. A compound of theformula ##STR27## wherein A is ##STR28## E is hydrogen, --CH₂ OH or--OH; and G and D are independently selected from hydrogen, C₁ to C₁₀alkyl, --OH, --CH₂ OH, --CH₂ OR₂₀ wherein R₂₀ is C₁ to C₆ alkyl, --CH₂OC(O)R₂₁ wherein R₂₁ is C₁ to C₁₀ alkyl, --CH₂ OC(O)CH(R₂₂)(NHR₂₃)wherein R₂₂ is the side chain of any of the naturally occuring aminoacids and R₂₃ is hydrogen or --C(O)CH(R₂₄) (NH₂) wherein R₂₄ is the sidechain of any of the naturally occuring amino acids. --CH₂ SH, --CH₂ Cl,--CH₂ F, --CH₂ Br, --CH₂ I, --C(O)H, --CH₂ CN, --CH₂ N₃, --CH₂ NR₁ R₂,--CO₂ R₁, --CH₂ CH₂ OH, --CH₂ CH₂ OR₂₀ wherein R₂₀ is as defined above.--CH₂ CH₂ OC(O)R₂₁ wherein R₂₁ is as defined above, --CH₂ CH₂OC(O)CH(R₂₂) (NMR₂₃) wherein R₂₂ and R₂₃ are as defined above, --CH₂ CH₂PO₃ H₂, --CH₂ OPO₃ H₂, --OCH₂ PO₃ H₂ and --CH₂ CO₂ R₃ wherein R₁ and R₂are independently selected from hydrogen and C₁ to C₁₀ alkyl, --NHC(O)R₃wherein R₃ is hydrogen, C₁ to C₁₀ alkyl, carboxyalkyl or aminoalkyl,--N═CHNR₄ R₅ wherein R₄ and R₅ are independently selected from C₁ to C₁₀alkyl, --N(R₆)OR₇ wherein R₆ and R₇ are independently selected fromhydrogen and C₁ to C₁₀ alkyl, and --N(R₈)NR₉ R₁₀ wherein R₈, R₉ and R₁₀are independently selected from hydrogen and C.sub. 1 to C₁₀ alkyl; withthe proviso that when E is --OH then D is not --OH and with the provisothat when E is hydrogen and D is hydrogen or C₁ to C₁₀ alkyl then G isnot hydrogen or C₁ to C₁₀ alkyl; and with the proviso that when E ishydrogen and D is --CH₂ OH, --CH₂ OPO₃ H₂ or --CH₂ OC(O)R₂₁ then G isother than --CH₂ OH, --CH₂ OPO₃ H₂ or --CH₂ OC(O)R₂₁ or when E ishydrogen and G is --CH₂ OH, --CH₂ OPO₃ H₂ or --CH₂ OC(O)R₂₁ then D isother that --CH₂ OH, --CH₂ OPO₃ H₂ or --CH₂ OC(O)R₂₁ ; or apharmaceutically acceptable salt thereof.
 5. A compound of the formula:##STR29## wherein A is ##STR30## E is hydrogen; and G and D areindependently selected from --CH₂ OH, --CH₂ OPO₃ H₂ and --CH₂ OC(O)R₂₁wherein R₂₁ is C₁ to C₁₀ alkyl; or a pharmaceutically acceptable saltthereof.
 6. An antiviral pharmaceutical composition comprising apharmaceutical carrier and a pharmaceutically effective amount of acompound of claim 1.